Vulnerability · Published Jan 30, 2026 · Assigned by GitHub_M
CVE-2026-25128fast-xml-parser has RangeError DoS Numeric Entities Bug
High 7.5
In plain English
A high-severity improper input validation in fast-xml-parser from NaturalIntelligence. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 5.0.9 through 5.3.3, a RangeError vulnerability exists in the numeric entity processing of fast-xml-parser when parsing XML with out-of-range entity code points (e.g., `�` or `�`). This causes the parser to throw an uncaught exception, crashing any application that processes untrusted XML input. Version 5.3.4 fixes the issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:24.04:LTS | node-webfont | no fix listed | UBUNTU-CVE-2026-25128 |
| Ubuntu:25.10 | node-webfont | no fix listed | UBUNTU-CVE-2026-25128 |
| Ubuntu:26.04:LTS | node-webfont | no fix listed | UBUNTU-CVE-2026-25128 |
| Ubuntu:26.10 | node-webfont | no fix listed | UBUNTU-CVE-2026-25128 |
| npm | fast-xml-parser | 5.3.4 | GHSA-37qj-frw5-hhjh |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| NaturalIntelligence | fast-xml-parser | >= 5.0.9, <= 5.3.3 |
Weakness: CWE-20, CWE-248 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-37qj-frw5-hhjh x_refsource_CONFIRM
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/4e387f61c4a5cef792f6a2f42467013290bf95dc x_refsource_MISC
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.4 x_refsource_MISC