{"id":"CVE-2026-27601","summary":"Underscore.js has unlimited recursion in _.flatten and _.isEqual, potential for DoS attack","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.","aliases":["GHSA-qpx9-hpmf-5gmw"],"modified":"2026-04-02T13:21:56.803771Z","published":"2026-03-03T22:38:38.955Z","related":["CGA-p6mm-848f-wjwh","openSUSE-SU-2026:10424-1","openSUSE-SU-2026:10427-1","openSUSE-SU-2026:10440-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27601.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-770"]},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/documentcloud/underscore","events":[{"introduced":"0"},{"fixed":"9374840c22e348083d0d072f30dc980622523259"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"1.13.8"}]}}],"versions":["0.1.0","0.1.1","0.2.0","0.3.0","0.3.1","0.3.2","0.3.3","0.4.0","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.7","0.5.0","0.5.1","0.5.2","0.5.3","0.5.4","0.5.5","0.5.6","0.5.7","0.5.8","0.6.0","1.0.0","1.0.1","1.0.2","1.0.3","1.0.4","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.1.7","1.10.0","1.10.1","1.10.2","1.11.0","1.12.0","1.12.1","1.13.0","1.13.0-0","1.13.0-1","1.13.0-2","1.13.0-3","1.13.1","1.13.2","1.13.3","1.13.4","1.13.5","1.13.6","1.13.7","1.2.0","1.2.1","1.2.2","1.2.3","1.2.4","1.3.0","1.3.1","1.3.2","1.3.3","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.5.0","1.5.1","1.5.2","1.6.0","1.7.0","1.8.0","1.8.1","1.8.2","1.8.3","1.9.0","1.9.1","1.9.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27601.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/jashkenas/underscore","events":[{"introduced":"0"},{"fixed":"9374840c22e348083d0d072f30dc980622523259"}]}],"versions":["0.1.0","0.1.1","0.2.0","0.3.0","0.3.1","0.3.2","0.3.3","0.4.0","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.7","0.5.0","0.5.1","0.5.2","0.5.3","0.5.4","0.5.5","0.5.6","0.5.7","0.5.8","0.6.0","1.0.0","1.0.1","1.0.2","1.0.3","1.0.4","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.1.7","1.10.0","1.10.1","1.10.2","1.11.0","1.12.0","1.12.1","1.13.0","1.13.0-0","1.13.0-1","1.13.0-2","1.13.0-3","1.13.1","1.13.2","1.13.3","1.13.4","1.13.5","1.13.6","1.13.7","1.2.0","1.2.1","1.2.2","1.2.3","1.2.4","1.3.0","1.3.1","1.3.2","1.3.3","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.5.0","1.5.1","1.5.2","1.6.0","1.7.0","1.8.0","1.8.1","1.8.2","1.8.3","1.9.0","1.9.1","1.9.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27601.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","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"}]}