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. 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.
Published: 2026-02-20
Score: 9.3 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

No remediation available yet.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-m7jm-9gc2-mpf2 fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
History

Mon, 02 Mar 2026 15:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:naturalintelligence:fast-xml-parser:*:*:*:*:*:*:*:*

Mon, 23 Feb 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 23 Feb 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Naturalintelligence
Naturalintelligence fast-xml-parser
Vendors & Products Naturalintelligence
Naturalintelligence fast-xml-parser

Sat, 21 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-79
References
Metrics threat_severity

None

threat_severity

Important


Fri, 20 Feb 2026 21:15:00 +0000

Type Values Removed Values Added
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. 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 (&lt;, &gt;, &amp;, &quot;, &apos;) with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.
Title fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names
Weaknesses CWE-185
References
Metrics cvssV3_1

{'score': 9.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N'}


Subscriptions

Naturalintelligence Fast-xml-parser
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-02T19:11:31.673Z

Reserved: 2026-02-06T21:08:39.130Z

Link: CVE-2026-25896

cve-icon Vulnrichment

Updated: 2026-02-23T19:27:50.880Z

cve-icon NVD

Status : Analyzed

Published: 2026-02-20T21:19:27.470

Modified: 2026-03-02T14:54:02.760

Link: CVE-2026-25896

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-20T20:57:48Z

Links: CVE-2026-25896 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-02-23T14:35:10Z

Weaknesses