CVSS 3.1
9.3 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:NCVE-2026-25896
Critical (9.3) in naturalintelligence fast-xml-parser. EPSS 0.5% chance of exploitation in the next 30 days. Fixed in fast-xml-parser 4.5.4, 5.3.5.
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. From 4.1.3to before 5.3.5, a dot (.) in a DOCTYPE entity name is treated as a regex wildcard during entity replacement, allowing an attacker to shadow built-in XML entities (<, >, &, ", ') with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.
Severity
- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 44% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-185, CWE-79
- Published
- Modified
- Record from
- the NVD, synced
Affected
- naturalintelligence:fast-xml-parser
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-m7jm-9gc2-mpf2 | npm | fast-xml-parser | >=5.0.0 <5.3.5 | 5.3.5 |
| GHSA-m7jm-9gc2-mpf2 | npm | fast-xml-parser | >=4.1.3 <4.5.4 | 4.5.4 |
References
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/943ef0eb1b2d3284e72dd74f44a042ee9f07026e
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/ddcd0acf26ddd682cb0dc15a2bd6aa3b96bb1e69
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.5
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-m7jm-9gc2-mpf2
- https://access.redhat.com/errata/RHSA-2026:40984