{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.13.8"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9374840c22e348083d0d072f30dc980622523259"
            }
          ],
          "repo": "https://github.com/documentcloud/underscore",
          "type": "GIT"
        }
      ]
    },
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "9374840c22e348083d0d072f30dc980622523259"
            }
          ],
          "repo": "https://github.com/jashkenas/underscore",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-qpx9-hpmf-5gmw"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27601.json"
  },
  "details": "Underscore.js is a utility-belt library for JavaScript. Prior to 1.13.8, the _.flatten and _.isEqual functions use recursion without a depth limit. Under very specific conditions, detailed below, an attacker could exploit this in a Denial of Service (DoS) attack by triggering a stack overflow. Untrusted input must be used to create a recursive datastructure, for example using JSON.parse, with no enforced depth limit. The datastructure thus created must be passed to _.flatten or _.isEqual. In the case of _.flatten, the vulnerability can only be exploited if it is possible for a remote client to prepare a datastructure that consists of arrays at all levels AND if no finite depth limit is passed as the second argument to _.flatten. In the case of _.isEqual, the vulnerability can only be exploited if there exists a code path in which two distinct datastructures that were submitted by the same remote client are compared using _.isEqual. For example, if a client submits data that are stored in a database, and the same client can later submit another datastructure that is then compared to the data that were saved in the database previously, OR if a client submits a single request, but its data are parsed twice, creating two non-identical but equivalent datastructures that are then compared. Exceptions originating from the call to _.flatten or _.isEqual, as a result of a stack overflow, are not being caught. This vulnerability is fixed in 1.13.8.",
  "id": "CVE-2026-27601",
  "modified": "2026-04-01T23:08:01.419289758Z",
  "published": "2026-03-03T22:38:38.955Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27601.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/jashkenas/underscore/security/advisories/GHSA-qpx9-hpmf-5gmw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27601"
    },
    {
      "type": "FIX",
      "url": "https://github.com/jashkenas/underscore/commit/411e222eb0ca5d570cc4f6315c02c05b830ed2b4"
    },
    {
      "type": "FIX",
      "url": "https://github.com/jashkenas/underscore/commit/a6e23ae9647461ec33ad9f92a2ecfc220eea0a84"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Underscore.js has unlimited recursion in _.flatten and _.isEqual, potential for DoS attack"
}