NaturalIntelligence fast-xml-parser up to 5.3.4 incorrect regex

CVSS Meta Temp Score
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CTI Interest Score
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8.1$0-$5k0.00

Summaryinfo

A vulnerability has been found in NaturalIntelligence fast-xml-parser up to 5.3.4 and classified as critical. This affects an unknown function. This manipulation causes incorrect regex. This vulnerability is registered as CVE-2026-25896. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in NaturalIntelligence fast-xml-parser up to 5.3.4. It has been declared as critical. Affected by this vulnerability is an unknown part. The manipulation with an unknown input leads to a incorrect regex vulnerability. The CWE definition for the vulnerability is CWE-185. The product specifies a regular expression in a way that causes data to be improperly matched or compared. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-25896 since 02/06/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 299725 (Linux Distros Unpatched Vulnerability : CVE-2026-25896), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.3.5 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 943ef0eb1b2d3284e72dd74f44a042ee9f07026e is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (299725) and CERT Bund (WID-SEC-2026-0772). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • IBM App Connect Enterprise

Productinfo

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.3
VulDB Meta Temp Score: 8.1

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.3
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Incorrect regex
CWE: CWE-185 / CWE-697
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 299725
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-25896

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: fast-xml-parser 5.3.5
Patch: 943ef0eb1b2d3284e72dd74f44a042ee9f07026e

Timelineinfo

02/06/2026 CVE reserved
02/21/2026 +15 days Advisory disclosed
02/21/2026 +0 days VulDB entry created
03/18/2026 +25 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-m7jm-9gc2-mpf2
Status: Confirmed

CVE: CVE-2026-25896 (🔒)
GCVE (CVE): GCVE-0-2026-25896
GCVE (VulDB): GCVE-100-347245
CERT Bund: WID-SEC-2026-0772 - IBM App Connect Enterprise (fast-xml-parser): Mehrere Schwachstellen

Entryinfo

Created: 02/21/2026 05:47
Updated: 03/18/2026 18:32
Changes: 02/21/2026 05:47 (66), 02/22/2026 00:02 (2), 02/22/2026 20:12 (1), 03/03/2026 05:21 (1), 03/18/2026 18:32 (7)
Complete: 🔍
Cache ID: 216::103

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