CVE-2026-76957

A flaw was found in libexpat. The library's handling of custom encoding callbacks lacks proper tracking of handler call depth, which can lead to a use-after-free vulnerability. This memory corruption flaw could allow a local attacker to cause a denial of service or potentially execute arbitrary code.

Red Hat ships libexpat (packaged as "expat") across many products. All versions of expat prior to 2.8.4 are affected by this use-after-free vulnerability. Exploitation requires triggering the vulnerable code path through custom encoding callbacks, which is not a common usage pattern.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.