Medium6.1Red Hat & Ubuntu Linux
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component
CVE-2026-8959 Published May 19, 2026
CVE-2026-8959
Affected products & platforms
Red Hat & Ubuntu LinuxUnclassified
Summary
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-653. Affected package(s): thunderbird. Resolved in Red Hat advisory RHSA-2026:21381 — update the affected packages (`sudo dnf update`).
Affected versions
- thunderbird-0:140.11.0-1.el8_8
- thunderbird-0:140.11.0-1.el9_8
- thunderbird-0:140.11.0-1.el10_2
- thunderbird-0:140.11.0-1.el8_10
- thunderbird-0:140.11.0-1.el8_4
- thunderbird-0:140.11.0-1.el10_0
- thunderbird-0:140.11.0-1.el9_4
- thunderbird-0:140.11.0-1.el8_6
- thunderbird-0:140.11.0-1.el9_6
- thunderbird-0:140.11.0-1.el9_2
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
Fixed versions
- RHSA-2026:21381
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
Mitigation checklist
Recommended fix / mitigation
- Update the affected package(s) to the fixed version shipped in RHSA-2026:21381 (`sudo dnf update` / `yum update`).
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
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