| Name | CVE-2026-74960 |
| Description | Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1. |
| 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-4750-1, DLA-4754-1, DSA-6451-1, DSA-6461-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| firefox (PTS) | sid | 155.0.1-1 | fixed |
| firefox-esr (PTS) | bookworm | 140.12.0esr-1~deb12u1 | vulnerable |
| bookworm (security) | 140.15.0esr-1~deb12u1 | fixed | |
| trixie | 140.12.0esr-1~deb13u1 | vulnerable | |
| trixie (security) | 140.15.0esr-1~deb13u1 | fixed | |
| forky, sid | 140.15.0esr-1 | fixed | |
| thunderbird (PTS) | bookworm | 1:140.12.0esr-1~deb12u1 | vulnerable |
| bookworm (security) | 1:140.15.0esr-1~deb12u1 | fixed | |
| trixie | 1:140.12.0esr-1~deb13u1 | vulnerable | |
| trixie (security) | 1:140.15.0esr-1~deb13u1 | fixed | |
| forky | 1:140.14.0esr-1 | fixed | |
| sid | 1:153.2.0esr-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) | 154.0-1 | |||
| firefox-esr | source | bullseye | 140.14.0esr-1~deb11u1 | DLA-4750-1 | ||
| firefox-esr | source | bookworm | 140.14.0esr-1~deb12u1 | DLA-4750-1 | ||
| firefox-esr | source | trixie | 140.14.0esr-1~deb13u1 | DSA-6451-1 | ||
| firefox-esr | source | (unstable) | 140.14.0esr-2 | |||
| thunderbird | source | bullseye | 1:140.14.0esr-1~deb11u1 | DLA-4754-1 | ||
| thunderbird | source | bookworm | 1:140.14.0esr-1~deb12u1 | DLA-4754-1 | ||
| thunderbird | source | trixie | 1:140.14.0esr-1~deb13u1 | DSA-6461-1 | ||
| thunderbird | source | (unstable) | 1:140.14.0esr-1 |
https://www.mozilla.org/en-US/security/advisories/mfsa2026-74/#CVE-2026-74960
https://www.mozilla.org/en-US/security/advisories/mfsa2026-76/#CVE-2026-74960
https://www.mozilla.org/en-US/security/advisories/mfsa2026-79/#CVE-2026-74960