CVE-2026-76957
Public on 2026-08-20
Modified on 2026-08-24
Description
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
CVSS v3 Base Score
See breakdown
Affected Packages
| Platform | Package | Release Date | Advisory | Status |
|---|---|---|---|---|
| Amazon Linux 2 - Core | expat | Pending Fix | ||
| Amazon Linux 2023 | expat | Pending Fix | ||
| Amazon Linux 2027 Preview | expat | Pending Fix | ||
| Amazon Linux 2 - Firefox Extra | firefox | 2026-08-31 | ALAS2FIREFOX-2026-064 | Fixed |
| Amazon Linux 2023 | firefox | 2026-08-31 | ALAS2023-2026-2105 | Fixed |
| Amazon Linux 2027 Preview | firefox | Pending Fix | ||
| Amazon Linux 2 - Core | thunderbird | 2026-08-31 | ALAS2-2026-3880 | Fixed |
| Amazon Linux 2023 | xmlrpc-c | Not Affected |
CVSS Scores
| Score Type | Score | Vector | |
|---|---|---|---|
| Amazon Linux | CVSSv3 | 4.9 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L |
| NVD | CVSSv3 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |