fast-xml-parser vulnerable to Regex Injection via Doctype Entities

Description

“fast-xml-parser” allows special characters in entity names, which are not escaped or sanitized. Since the entity name is used for creating a regex for searching and replacing entities in the XML body, an attacker can abuse it for DoS attacks.

Recommendation

Update the fast-xml-parser package to the latest compatible version. Followings are version details:

• Affected version(s): >= 4.1.3, < 4.2.4
• Patched version(s): 4.2.4

References

• GHSA-6w63-h3fj-q4vw
• CVE-2023-34104
• CWE-1333
• CWE-400
• CAPEC-310
• OWASP 2021-A6

Related Issues

• fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names - CVE-2026-25896
• fast-xml-parser vulnerable to Prototype Pollution through tag or attribute name - CVE-2023-26920
• fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit) - CVE-2026-26278
• fast-xml-parser has RangeError DoS Numeric Entities Bug - CVE-2026-25128

Tags:

npm

fast-xml-parser