libexpat up to 2.7.5 XML Document entropy

CVSS Meta Temp Score
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CTI Interest Score
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4.3$0-$5k0.00

Summaryinfo

A vulnerability identified as problematic has been detected in libexpat up to 2.7.5. Affected is an unknown function of the component XML Document Handler. This manipulation causes entropy. This vulnerability is handled as CVE-2026-41080. It is possible to launch the attack on the local host. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in libexpat up to 2.7.5 and classified as problematic. Affected by this vulnerability is some unknown functionality of the component XML Document Handler. The manipulation with an unknown input leads to a entropy vulnerability. The CWE definition for the vulnerability is CWE-331. The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others. As an impact it is known to affect confidentiality. The summary by CVE is:

libexpat before 2.8.0 uses insufficient entropy, and thus hash flooding can occur via a crafted XML document.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-41080 since 04/16/2026. The exploitation appears to be difficult. An attack has to be approached locally. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1600.001 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 316996 (Amazon Linux 2 : firefox, --advisory ALAS2FIREFOX-2026-059 (ALASFIREFOX-2026-059)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.7.6 eliminates this vulnerability. Applying a patch 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 (316996), EUVD (EUVD-2026-23276) and CERT Bund (WID-SEC-2026-1159). Several companies clearly confirm that VulDB is the primary source for best 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: 4.3
VulDB Meta Temp Score: 4.3

VulDB Base Score: 2.5
VulDB Temp Score: 2.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 2.9
CNA Vector (MITRE): 🔒

ADP CISA Base Score: 7.5
ADP CISA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Entropy
CWE: CWE-331 / CWE-330 / CWE-310
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 316996
Nessus Name: Amazon Linux 2 : firefox, --advisory ALAS2FIREFOX-2026-059 (ALASFIREFOX-2026-059)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: libexpat 2.7.6
Patch: github.com

Timelineinfo

04/16/2026 Advisory disclosed
04/16/2026 +0 days CVE reserved
04/16/2026 +0 days VulDB entry created
06/12/2026 +57 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: 47
Status: Confirmed

CVE: CVE-2026-41080 (🔒)
GCVE (CVE): GCVE-0-2026-41080
GCVE (VulDB): GCVE-100-357961
EUVD: 🔒
CERT Bund: WID-SEC-2026-1159 - expat: Schwachstelle ermöglicht Denial of Service

Entryinfo

Created: 04/16/2026 21:42
Updated: 06/12/2026 20:56
Changes: 04/16/2026 21:42 (65), 04/16/2026 21:54 (1), 04/17/2026 11:17 (7), 05/29/2026 12:48 (2), 06/12/2026 20:56 (12)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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