GHSA-2G4F-4PWH-QVX6

Vulnerability from github – Published: 2026-02-11 21:30 – Updated: 2026-02-23 22:40
VLAI?
Summary
ajv has ReDoS when using `$data` option
Details

ajv (Another JSON Schema Validator) through version 8.17.1 is vulnerable to Regular Expression Denial of Service (ReDoS) when the $data option is enabled. The pattern keyword accepts runtime data via JSON Pointer syntax ($data reference), which is passed directly to the JavaScript RegExp() constructor without validation. An attacker can inject a malicious regex pattern (e.g., \"^(a|a)*$\") combined with crafted input to cause catastrophic backtracking. A 31-character payload causes approximately 44 seconds of CPU blocking, with each additional character doubling execution time. This enables complete denial of service with a single HTTP request against any API using ajv with $data: true for dynamic schema validation.

Severity ?
5.5 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "ajv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0-alpha.0"
            },
            {
              "fixed": "8.18.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "ajv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.14.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-69873"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333",
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-17T16:38:57Z",
    "nvd_published_at": "2026-02-11T19:15:50Z",
    "severity": "MODERATE"
  },
  "details": "ajv (Another JSON Schema Validator) through version 8.17.1 is vulnerable to Regular Expression Denial of Service (ReDoS) when the `$data` option is enabled. The pattern keyword accepts runtime data via JSON Pointer syntax (`$data` reference), which is passed directly to the JavaScript `RegExp()` constructor without validation. An attacker can inject a malicious regex pattern (e.g., `\\\"^(a|a)*$\\\"`) combined with crafted input to cause catastrophic backtracking. A 31-character payload causes approximately 44 seconds of CPU blocking, with each additional character doubling execution time. This enables complete denial of service with a single HTTP request against any API using ajv with `$data`: true for dynamic schema validation.",
  "id": "GHSA-2g4f-4pwh-qvx6",
  "modified": "2026-02-23T22:40:29Z",
  "published": "2026-02-11T21:30:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-69873"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ajv-validator/ajv/pull/2586"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ajv-validator/ajv/pull/2588"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ajv-validator/ajv/commit/720a23fa453ffae8340e92c9b0fe886c54cfe0d5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/EthanKim88/ethan-cve-disclosures/blob/main/CVE-2025-69873-ajv-ReDoS.md"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-2g4f-4pwh-qvx6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ajv-validator/ajv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ajv-validator/ajv/releases/tag/v6.14.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ajv-validator/ajv/releases/tag/v8.18.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "ajv has ReDoS when using `$data` option"
}


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