RLSA-2026:2220

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

• firefox: Spoofing issue in the Downloads Panel component (CVE-2025-14327)

• firefox: Use-after-free in the JavaScript: GC component (CVE-2026-0885)

• firefox: thunderbird: Memory safety bugs fixed in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147 (CVE-2026-0891)

• firefox: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component (CVE-2026-0878)

• firefox: Use-after-free in the IPC component (CVE-2026-0882)

• firefox: Use-after-free in the JavaScript Engine component (CVE-2026-0884)

• firefox: Information disclosure in the Networking component (CVE-2026-0883)

• firefox: Mitigation bypass in the DOM: Security component (CVE-2026-0877)

• firefox: Spoofing issue in the DOM: Copy & Paste and Drag & Drop component (CVE-2026-0890)

• firefox: Clickjacking issue, information disclosure in the PDF Viewer component (CVE-2026-0887)

• firefox: Sandbox escape due to incorrect boundary conditions in the Graphics component (CVE-2026-0879)

• firefox: Sandbox escape due to integer overflow in the Graphics component (CVE-2026-0880)

• firefox: Incorrect boundary conditions in the Graphics component (CVE-2026-0886)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.