CVE-2026-25128

fast-xml-parser has RangeError DoS Numeric Entities Bug

HIGH
7.5
CVSS Score
Published: January 30, 2026 at 03:14 PM UTC
Updated: June 17, 2026 at 10:24 AM UTC
1 product affected across 1 vendorFast XML Parser

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Severity
HIGH7.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

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 4.3.6 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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 5.3.35.0.9 ≤ v < 5.3.4

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-20CWE-248

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