{"id":"CVE-2026-26278","aliases":["GHSA-jmr7-xgp7-cmfj"],"url":"https://o3.security/vulnerability/CVE-2026-26278","summary":"fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit)","details":"fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.","published":"2026-02-19T19:40:55.842Z","modified":"2026-09-12T03:31:03.854535130Z","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":0.00843,"percentile":0.56224,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"fast-xml-parser","fixedVersion":"4.5.4"},{"ecosystem":"npm","name":"fast-xml-parser","fixedVersion":"5.3.6"}],"fix":{"url":"https://github.com/NaturalIntelligence/fast-xml-parser/commit/910dae5be2de2955e968558fadf6e8f74f117a77","label":"NaturalIntelligence/fast-xml-parser@910dae5"},"references":[{"type":"WEB","url":"https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.6"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26278.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:40984"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:41941"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:41944"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:51349"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6174"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6802"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7110"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7128"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-26278"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26278.json"},{"type":"ADVISORY","url":"https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jmr7-xgp7-cmfj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26278"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2441120"},{"type":"FIX","url":"https://github.com/NaturalIntelligence/fast-xml-parser/commit/910dae5be2de2955e968558fadf6e8f74f117a77"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-12T03:31:03.854535130Z"}}