| Name | CVE-2026-2776 |
| Description | Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-4495-1, DLA-4496-1, DSA-6148-1, DSA-6152-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| firefox (PTS) | sid | 150.0-1 | fixed |
| firefox-esr (PTS) | bullseye | 115.14.0esr-1~deb11u1 | vulnerable |
| bullseye (security) | 140.10.0esr-1~deb11u1 | fixed | |
| bookworm | 128.14.0esr-1~deb12u1 | vulnerable | |
| bookworm (security) | 140.10.0esr-1~deb12u1 | fixed | |
| trixie | 140.8.0esr-1~deb13u1 | fixed | |
| trixie (security) | 140.10.0esr-1~deb13u1 | fixed | |
| forky | 140.9.1esr-1 | fixed | |
| sid | 140.10.0esr-1 | fixed | |
| thunderbird (PTS) | bullseye | 1:115.12.0-1~deb11u1 | vulnerable |
| bullseye (security) | 1:140.10.0esr-1~deb11u1 | fixed | |
| bookworm | 1:140.6.0esr-1~deb12u1 | vulnerable | |
| bookworm (security) | 1:140.10.0esr-1~deb12u1 | fixed | |
| trixie | 1:140.8.0esr-1~deb13u1 | fixed | |
| trixie (security) | 1:140.10.0esr-1~deb13u1 | fixed | |
| forky | 1:140.9.1esr-1 | fixed | |
| sid | 1:140.10.0esr-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| firefox | source | (unstable) | 148.0-1 | |||
| firefox-esr | source | bullseye | 140.8.0esr-1~deb11u1 | DLA-4496-1 | ||
| firefox-esr | source | bookworm | 140.8.0esr-1~deb12u1 | DSA-6148-1 | ||
| firefox-esr | source | trixie | 140.8.0esr-1~deb13u1 | DSA-6148-1 | ||
| firefox-esr | source | (unstable) | 140.8.0esr-1 | |||
| thunderbird | source | bullseye | 1:140.8.0esr-1~deb11u1 | DLA-4495-1 | ||
| thunderbird | source | bookworm | 1:140.8.0esr-1~deb12u1 | DSA-6152-1 | ||
| thunderbird | source | trixie | 1:140.8.0esr-1~deb13u1 | DSA-6152-1 | ||
| thunderbird | source | (unstable) | 1:140.8.0esr-1 |
https://www.mozilla.org/en-US/security/advisories/mfsa2026-13/#CVE-2026-2776
https://www.mozilla.org/en-US/security/advisories/mfsa2026-15/#CVE-2026-2776
https://www.mozilla.org/en-US/security/advisories/mfsa2026-17/#CVE-2026-2776