{"id":"CVE-2026-4926","aliases":["GHSA-j3q9-mxjg-w52f"],"url":"https://o3.security/vulnerability/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.","published":"2026-03-26T18:59:38Z","modified":"2026-09-18T03:31:04.953344037Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00791,"percentile":0.54602,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"path-to-regexp","fixedVersion":"8.4.0"}],"fix":null,"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4926.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:10153"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:10172"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:10175"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13545"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13826"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:17789"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:19409"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:19410"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:24761"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:24762"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:24866"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:36651"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:40118"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:40945"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:50300"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:65126"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:9385"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:9742"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-4926"},{"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"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2451867"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-18T03:31:04.953344037Z"}}