Vulnerability-Lookup

CVE-2026-41148 (GCVE-0-2026-41148)

Vulnerability from cvelistv5 – Published: 2026-05-22 22:03 – Updated: 2026-05-27 13:25

Title

Mermaid: Improper sanitization of `classDefs` in diagrams leads to CSS injection

Summary

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and prior, in addition to 11.0.0-alpha.1 through 11.12.0 are vulnerable to CSS injection through improper sanitization. The state diagram (and any other diagram type that routes user-controlled style strings through the createCssStyles parser) captures classDef values using an unrestricted regex that matches everything up to a newline. That value then flows unsanitized through addStyleClass() into createCssStyles() and is assigned to style.innerHTML, so a closing brace (}) in the value terminates the generated CSS selector and turns everything after it into a new CSS rule on the page. This enables page defacement, user tracking via url() callbacks, and DOM attribute exfiltration. This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting "securityLevel": "sandbox", which prevents the issue by rendering the mermaid diagram in a sandboxed <iframe>.

Severity

5.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

GitHub_M

References

6 references

URL	Tags
https://github.com/mermaid-js/mermaid/security/ad…	x_refsource_CONFIRM
https://github.com/mermaid-js/mermaid/commit/8fea…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/commit/e9b0…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/releases/ta…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/releases/ta…	x_refsource_MISC
https://mermaid.js.org/config/schema-docs/config.…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
mermaid-js	mermaid	Affected: >= 11.0.0-alpha.1, < 11.15.0 Affected: < 10.9.6

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-41148

Vulnerability from fkie_nvd - Published: 2026-05-22 23:16 - Updated: 2026-06-17 10:46

Severity

5.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/mermaid-js/mermaid/commit/8fead23c59166b7bab6a39eac81acebee2859102
	security-advisories@github.com	https://github.com/mermaid-js/mermaid/commit/e9b0f34d8d82a6260077764ee45e1d7d90957a0f
	security-advisories@github.com	https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0
	security-advisories@github.com	https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6
	security-advisories@github.com	https://github.com/mermaid-js/mermaid/security/advisories/GHSA-xcj9-5m2h-648r
	security-advisories@github.com	https://mermaid.js.org/config/schema-docs/config.html#securitylevel

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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    {
      "affectedData": [
        {
          "product": "mermaid",
          "vendor": "mermaid-js",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 11.0.0-alpha.1, \u003c 11.15.0"
            },
            {
              "status": "affected",
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            }
          ]
        }
      ],
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    }
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    }
  ],
  "id": "CVE-2026-41148",
  "lastModified": "2026-06-17T10:46:14.373",
  "metrics": {
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        "cvssData": {
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          "baseSeverity": "MEDIUM",
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          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-41148",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-27T13:25:29.202814Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-22T23:16:53.593",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/commit/8fead23c59166b7bab6a39eac81acebee2859102"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/commit/e9b0f34d8d82a6260077764ee45e1d7d90957a0f"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-xcj9-5m2h-648r"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://mermaid.js.org/config/schema-docs/config.html#securitylevel"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-94"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-XCJ9-5M2H-648R

Vulnerability from github – Published: 2026-05-11 19:36 – Updated: 2026-06-08 23:20

Summary

Mermaid: Improper sanitization of `classDefs` in diagrams leads to CSS injection

Details

The state diagram and any other diagram type that routes user-controlled style strings through createCssStyles parser for Mermaid v11.14.0 and earlier captures classDef values with an unrestricted regex:

// packages/mermaid/src/diagrams/state/parser/stateDiagram.jison:83
<CLASSDEFID>[^\n]*   { this.popState(); return 'CLASSDEF_STYLEOPTS' }

The value passes unsanitized through addStyleClass() -> createCssStyles() -> style.innerHTML (mermaidAPI.ts:418). A } in the value closes the generated CSS selector, and everything after becomes a new CSS rule on the page.

PoC

stateDiagram-v2 
      classDef x }*{ background-image: url("http://media.giphy.com/media/SggILpMXO7Xt6/giphy.gif")}

Live demo: https://mermaid.live/edit#pako:eNpFjzFvgzAQhf-KdVNbEcBgMHhtlkqtOnSJKi8ONsYKBmRMlRTx3-skanvTfbp7996t0IxSAYPZC6_2Rmgn7O4rQ00v5nmvWnRG29OKjqI5aTcug9wZK7RiaHH9A4fO-4kliVXSiFibqbvEzWjvnHxo_fI6vR3e6cGXyX2qTcvhcYMItDMSmHeLisAqZ8UVYeUDQhx8p6ziwEIrhTtx4MNVM4nhcxztrywE0h2wVvRzoGWS_z_8rahBKvcckntgmN5OAFvhDIzUNCZZQXCR5nVaZkUEF2BVFpOcEkoxxhUuyRbB980yjStapKHqoKFlhvPtB7BFZEU

Patches

This has been patched in:

Workarounds

Setting "securityLevel": "sandbox" will prevent this, by rendering the mermaid diagram in a sandboxed <iframe>.

Impact

Enables page defacement, user tracking via url() callbacks, and DOM attribute exfiltration via CSS :has() selectors.

Severity

5.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 11.14.0"
      },
      "package": {
        "ecosystem": "npm",
        "name": "mermaid"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.0.0-alpha.1"
            },
            {
              "fixed": "11.15.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 10.9.5"
      },
      "package": {
        "ecosystem": "npm",
        "name": "mermaid"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "10.9.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-41148"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-11T19:36:41Z",
    "nvd_published_at": "2026-05-22T23:16:53Z",
    "severity": "MODERATE"
  },
  "details": "### Details\n\nThe state diagram and any other diagram type that routes user-controlled style strings through createCssStyles parser for Mermaid v11.14.0 and earlier captures `classDef` values with an unrestricted regex:\n\n```jison\n// packages/mermaid/src/diagrams/state/parser/stateDiagram.jison:83\n\u003cCLASSDEFID\u003e[^\\n]*   { this.popState(); return \u0027CLASSDEF_STYLEOPTS\u0027 }\n```\n\nThe value passes unsanitized through `addStyleClass()` -\u003e `createCssStyles()` -\u003e `style.innerHTML` (mermaidAPI.ts:418). A `}` in the value closes the generated CSS selector, and everything after becomes a new CSS rule on the page.\n\n### PoC\n\n```\nstateDiagram-v2 \n      classDef x }*{ background-image: url(\"http://media.giphy.com/media/SggILpMXO7Xt6/giphy.gif\")}\n```\n\nLive demo:\n\u003chttps://mermaid.live/edit#pako:eNpFjzFvgzAQhf-KdVNbEcBgMHhtlkqtOnSJKi8ONsYKBmRMlRTx3-skanvTfbp7996t0IxSAYPZC6_2Rmgn7O4rQ00v5nmvWnRG29OKjqI5aTcug9wZK7RiaHH9A4fO-4kliVXSiFibqbvEzWjvnHxo_fI6vR3e6cGXyX2qTcvhcYMItDMSmHeLisAqZ8UVYeUDQhx8p6ziwEIrhTtx4MNVM4nhcxztrywE0h2wVvRzoGWS_z_8rahBKvcckntgmN5OAFvhDIzUNCZZQXCR5nVaZkUEF2BVFpOcEkoxxhUuyRbB980yjStapKHqoKFlhvPtB7BFZEU\u003e\n\n### Patches\n\nThis has been patched in:\n\n- [v11.15.0](https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0) (see [e9b0f34d8d82a6260077764ee45e1d7d90957a0f](https://github.com/mermaid-js/mermaid/commit/e9b0f34d8d82a6260077764ee45e1d7d90957a0f))\n- [v10.9.6](https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6) (see [8fead23c59166b7bab6a39eac81acebee2859102](https://github.com/mermaid-js/mermaid/commit/8fead23c59166b7bab6a39eac81acebee2859102))\n\n### Workarounds\n\nSetting [`\"securityLevel\": \"sandbox\"`](https://mermaid.js.org/config/schema-docs/config.html#securitylevel)  will prevent this, by rendering the mermaid diagram in a sandboxed `\u003ciframe\u003e`.\n\n### Impact\n\n Enables page defacement, user tracking via `url()` callbacks, and DOM attribute exfiltration via CSS `:has()` selectors.",
  "id": "GHSA-xcj9-5m2h-648r",
  "modified": "2026-06-08T23:20:59Z",
  "published": "2026-05-11T19:36:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-xcj9-5m2h-648r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41148"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/commit/8fead23c59166b7bab6a39eac81acebee2859102"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/commit/e9b0f34d8d82a6260077764ee45e1d7d90957a0f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mermaid-js/mermaid"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    },
    {
      "type": "WEB",
      "url": "https://mermaid.js.org/config/schema-docs/config.html#securitylevel"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Mermaid: Improper sanitization of `classDefs` in diagrams leads to CSS injection"
}

ubuntu-cve-2026-41148

Vulnerability from osv_ubuntu

Published

2026-05-22 23:16

Modified

2026-05-27 19:09

Summary

Details

Severity

5.3 (Medium)


                    
                      CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-41148	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-41148	REPORT
	https://github.com/mermaid-js/mermaid/security/ad…	REPORT
	https://github.com/mermaid-js/mermaid/commit/8fea…	REPORT
	https://github.com/mermaid-js/mermaid/commit/e9b0…	REPORT
	https://github.com/mermaid-js/mermaid/releases/ta…	REPORT
	https://github.com/mermaid-js/mermaid/releases/ta…	REPORT
	https://mermaid.js.org/config/schema-docs/config.…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-mermaid",
            "binary_version": "8.13.8+~cs10.4.16-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "node-mermaid",
        "purl": "pkg:deb/ubuntu/node-mermaid@8.13.8+~cs10.4.16-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.7.0+ds+~cs27.17.17-3",
        "8.13.3+ds+~cs26.13.21-1",
        "8.13.3+ds+~cs26.13.21-2",
        "8.13.8+~cs10.4.16-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Versions 10.9.5 and prior, in addition to 11.0.0-alpha.1 through 11.12.0 are vulnerable to CSS injection through improper sanitization. The state diagram (and any other diagram type that routes user-controlled style strings through the createCssStyles parser) captures classDef values using an unrestricted regex that matches everything up to a newline. That value then flows unsanitized through addStyleClass() into createCssStyles() and is assigned to style.innerHTML, so a closing brace (}) in the value terminates the generated CSS selector and turns everything after it into a new CSS rule on the page. This enables page defacement, user tracking via url() callbacks, and DOM attribute exfiltration. This issue has been fixed in versions 10.9.6 and 11.15.0. If developers are unable to immediately upgrade, they can work around this issue by setting \"securityLevel\": \"sandbox\", which prevents the issue by rendering the mermaid diagram in a sandboxed \u003ciframe\u003e.",
  "id": "UBUNTU-CVE-2026-41148",
  "modified": "2026-05-27T19:09:50Z",
  "published": "2026-05-22T23:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-41148"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-41148"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-xcj9-5m2h-648r"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/commit/8fead23c59166b7bab6a39eac81acebee2859102"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/commit/e9b0f34d8d82a6260077764ee45e1d7d90957a0f"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    },
    {
      "type": "REPORT",
      "url": "https://mermaid.js.org/config/schema-docs/config.html#securitylevel"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-41148"
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-41148 (GCVE-0-2026-41148)

FKIE_CVE-2026-41148

GHSA-XCJ9-5M2H-648R

Details

PoC

Patches

Workarounds

Impact

ubuntu-cve-2026-41148

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature