CVE-2026-2776

Details

Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.

Affected Packages

Firefox

Ubuntu 14.04 LTSUbuntu 16.04 LTSUbuntu 18.04 LTSUbuntu 20.04 LTSUbuntu 22.04 LTS

Fixed in:

148

Mozilla Firefox

Windows 10 (1507)Windows 10 (1607) / Server 2016Windows 10 (1809) / Server 2019Windows 10 (1903)Windows 10 (1909)

Fixed in:

148

Mozilla Firefox ESR

Windows 10 (1507)Windows 10 (1607) / Server 2016Windows 10 (1809) / Server 2019Windows 10 (1903)Windows 10 (1909)

Fixed in:

115.33

Mozilla Firefox ESR

Windows 10 (1507)Windows 10 (1607) / Server 2016Windows 10 (1809) / Server 2019Windows 10 (1903)Windows 10 (1909)

Fixed in:

140.8

Firefox ESR

macOS 14macOS 15macOS 26

Fixed in:

115.33

Firefox ESR

macOS 14macOS 15macOS 26

Fixed in:

140.8

References

WEB

https://bugzilla.mozilla.org/show_bug.cgi?id=2015266

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-2776

WEB

https://www.mozilla.org/security/advisories/mfsa2026-13/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-14/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-15/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-16/

WEB

https://www.mozilla.org/security/advisories/mfsa2026-17/