Unchecked Return Value in expat - CVE-2026-76956
Published: September 15, 2026
Vulnerability identifier: #VU149948
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-76956
CWE-ID: CWE-252
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inverted getentropy() return handling in the entropy extraction logic when initializing hash randomization. A remote attacker can conduct a hash-flooding attack to cause a denial of service.
The issue applies where getentropy is configured or detected as the only high-quality entropy extractor.
Affected software
expat
Fedora
mingw-expat
Fedora
mingw-expat
How to mitigate CVE-2026-76956
Install security update from vendor's website.
expat - update to 2.8.4
mingw-expat - addressed in versions 2.8.4-1.fc43, 2.8.4-1.fc44, 2.8.4-1.fc45
mingw-expat - addressed in versions 2.8.4-1.fc43, 2.8.4-1.fc44, 2.8.4-1.fc45