High7.5Red Hat & Ubuntu Linux
Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component
CVE-2026-2778 Published Feb 24, 2026
CVE-2026-2778
Affected products & platforms
Red Hat & Ubuntu LinuxUnclassified
Summary
Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. Red Hat rates this important (CVSS 7.5). Affected package(s): thunderbird, firefox. Resolved in Red Hat advisory RHSA-2026:3984 — update the affected packages (`sudo dnf update`).
Affected versions
- thunderbird-0:140.8.0-1.el9_0
- thunderbird-0:140.8.0-1.el8_6
- thunderbird-0:140.8.0-1.el9_6
- thunderbird-0:140.8.0-1.el8_8
- thunderbird-0:140.8.0-1.el9_7
- thunderbird-0:140.8.0-1.el8_2
- thunderbird-0:140.8.0-1.el9_2
- thunderbird-0:140.8.0-1.el9_4
- thunderbird-0:140.8.0-1.el8_10
- firefox-0:140.8.0-2.el8_2
- firefox-0:140.8.0-2.el9_0
- firefox-0:140.8.0-2.el8_4
Official advisory · high-confidence parse· fetched 4 hours ago·verify at source
Fixed versions
- RHSA-2026:3984
Official advisory · high-confidence parse· fetched 4 hours ago·verify at source
Mitigation checklist
Recommended fix / mitigation
- Update the affected package(s) to the fixed version shipped in RHSA-2026:3984 (`sudo dnf update` / `yum update`).
Official advisory · high-confidence parse· fetched 4 hours ago·verify at source
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