{"cve":"CVE-2026-33349","nvd":{"published":"2026-03-24T20:16:29.407","modified":"2026-06-17T10:37:21.500","status":"Analyzed","description":"fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. From version 4.0.0-beta.3 to before version 5.5.7, the DocTypeReader in fast-xml-parser uses JavaScript truthy checks to evaluate maxEntityCount and maxEntitySize configuration limits. When a developer explicitly sets either limit to 0 — intending to disallow all entities or restrict entity size to zero bytes — the falsy nature of 0 in JavaScript causes the guard conditions to short-circuit, completely bypassing the limits. An attacker who can supply XML input to such an application can trigger unbounded entity expansion, leading to memory exhaustion and denial of service. This issue has been patched in version 5.5.7.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9},"cwes":["CWE-1284"],"references":["https://github.com/NaturalIntelligence/fast-xml-parser/commit/239b64aa1fc5c5455ddebbbb54a187eb68c9fdb7","https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jp2q-39xq-3w4g","https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jp2q-39xq-3w4g"],"products":["naturalintelligence:fast-xml-parser"],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-33349","score":0.00467,"percentile":0.40444,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-jp2q-39xq-3w4g","url":"https://osv.dev/vulnerability/GHSA-jp2q-39xq-3w4g","summary":"Entity Expansion Limits Bypassed When Set to Zero Due to JavaScript Falsy Evaluation in fast-xml-parser","modified":"2026-09-10T03:50:39.873055407Z","packages":[{"ecosystem":"npm","name":"fast-xml-parser","purl":"pkg:npm/fast-xml-parser","ranges":[">=4.0.0-beta.3 <4.5.5"],"fixed":["4.5.5"]},{"ecosystem":"npm","name":"fast-xml-parser","purl":"pkg:npm/fast-xml-parser","ranges":[">=5.0.0 <5.5.7"],"fixed":["5.5.7"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}