{"id":"CVE-2026-4926","summary":"path-to-regexp vulnerable to Denial of Service via sequential optional groups","details":"Impact:\n\nA bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service.\n\nPatches:\n\nFixed in version 8.4.0.\n\nWorkarounds:\n\nLimit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.","aliases":["GHSA-j3q9-mxjg-w52f"],"modified":"2026-05-18T06:00:18.618632413Z","published":"2026-03-26T18:59:38Z","related":["CGA-4rwm-wmf3-xv3m"],"database_specific":{"unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"8.0.0"},{"fixed":"8.4.0"}]}],"cwe_ids":["CWE-1333","CWE-400"],"cna_assigner":"openjs","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4926.json"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/4xxx/CVE-2026-4926.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-4926"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pillarjs/path-to-regexp","events":[{"introduced":"ed1095e0fa78a692e7f3d489e383e7bb1f9d2cc4"},{"fixed":"34cb451ddaeea4783a2fe60579ffb3e4ccfc73a7"}],"database_specific":{"source":"CPE_FIELD","cpe":"cpe:2.3:a:pillarjs:path-to-regexp:*:*:*:*:*:node.js:*:*","extracted_events":[{"introduced":"8.0.0"},{"fixed":"8.4.0"}]}}],"versions":["v8.3.0","v8.2.0","v8.1.0","v8.0.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-4926.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}