libexpat up to 2.8.1 integer overflow

CVSS Meta Temp Score
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CTI Interest Score
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5.6$0-$5k3.70-

Summaryinfo

A vulnerability was found in libexpat up to 2.8.1. It has been classified as problematic. The impacted element is an unknown function. This manipulation causes integer overflow. This vulnerability appears as CVE-2026-56408. The attack requires local access. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in libexpat up to 2.8.1. It has been declared as problematic. Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a integer overflow vulnerability. The CWE definition for the vulnerability is CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. As an impact it is known to affect confidentiality, integrity, and availability.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-56408 since 06/21/2026. The exploitation appears to be difficult. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 321885 (Linux Distros Unpatched Vulnerability : CVE-2026-56408), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.8.2 eliminates this vulnerability. Applying the patch 16e2efd867ea8567ffa012210b52ef5918e20817 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 (321885), EUVD (EUVD-2026-38185) and CERT Bund (WID-SEC-2026-2025). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Open Source expat

Productinfo

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.6

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

CNA Base Score: 6.9
CNA Vector (MITRE): 🔒

CVSSv2info

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

Exploitinginfo

Class: Integer overflow
CWE: CWE-190 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

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

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Nessus ID: 321885
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-56408

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: libexpat 2.8.2
Patch: 16e2efd867ea8567ffa012210b52ef5918e20817

Timelineinfo

06/21/2026 Advisory disclosed
06/21/2026 +0 days CVE reserved
06/21/2026 +0 days VulDB entry created
06/22/2026 +1 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: 16e2efd867ea8567ffa012210b52ef5918e20817
Status: Confirmed

CVE: CVE-2026-56408 (🔒)
GCVE (CVE): GCVE-0-2026-56408
GCVE (VulDB): GCVE-100-372643
EUVD: 🔒
CERT Bund: WID-SEC-2026-2025 - libexpat: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

Entryinfo

Created: 06/21/2026 19:18
Updated: 06/22/2026 14:13
Changes: 06/21/2026 19:18 (63), 06/21/2026 20:25 (1), 06/22/2026 12:52 (7), 06/22/2026 14:13 (2)
Complete: 🔍
Cache ID: 216::103

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

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