libexpat up to 2.8.1 use after free

CVSS Meta Temp Score
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CTI Interest Score
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4.6$0-$5k3.04

Summaryinfo

A vulnerability was found in libexpat up to 2.8.1. It has been classified as critical. Affected by this issue is some unknown functionality. This manipulation causes use after free. This vulnerability is tracked as CVE-2026-56131. The attack is restricted to local execution. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in libexpat up to 2.8.1 and classified as critical. Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219 situation).

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-56131 since 06/19/2026. The exploitation appears to be difficult. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 2.8.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-2008). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Open Source expat

Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.7
VulDB Meta Temp Score: 4.6

VulDB Base Score: 4.5
VulDB Temp Score: 4.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.9
CNA Vector (MITRE): 🔒

CVSSv2info

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

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: libexpat 2.8.2

Timelineinfo

06/19/2026 Advisory disclosed
06/19/2026 +0 days CVE reserved
06/19/2026 +0 days VulDB entry created
06/19/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-56131 (🔒)
GCVE (CVE): GCVE-0-2026-56131
GCVE (VulDB): GCVE-100-372307
CERT Bund: WID-SEC-2026-2008 - expat: Mehrere Schwachstellen

Entryinfo

Created: 06/19/2026 07:55
Updated: 06/19/2026 11:31
Changes: 06/19/2026 07:55 (62), 06/19/2026 11:31 (7)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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