| Name | CVE-2026-84120 |
| Description | Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2. |
| 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 | DSA-6481-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| firefox (PTS) | sid | 155.0-1 | fixed |
| firefox-esr (PTS) | bookworm | 140.12.0esr-1~deb12u1 | vulnerable |
| bookworm (security) | 140.14.0esr-1~deb12u1 | vulnerable | |
| trixie | 140.12.0esr-1~deb13u1 | vulnerable | |
| trixie (security) | 140.14.0esr-1~deb13u1 | vulnerable | |
| forky | 140.14.0esr-2 | vulnerable | |
| sid | 140.15.0esr-1 | fixed | |
| thunderbird (PTS) | bookworm | 1:140.12.0esr-1~deb12u1 | vulnerable |
| bookworm (security) | 1:140.14.0esr-1~deb12u1 | vulnerable | |
| trixie | 1:140.12.0esr-1~deb13u1 | vulnerable | |
| trixie (security) | 1:140.14.0esr-1~deb13u1 | vulnerable | |
| forky | 1:140.14.0esr-1 | vulnerable | |
| 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) | 155.0-1 | |||
| firefox-esr | source | trixie | 140.15.0esr-1~deb13u1 | DSA-6481-1 | ||
| firefox-esr | source | (unstable) | 140.15.0esr-1 | |||
| thunderbird | source | (unstable) | 1:153.2.0esr-1 |
https://www.mozilla.org/en-US/security/advisories/mfsa2026-82/#CVE-2026-84120
https://www.mozilla.org/en-US/security/advisories/mfsa2026-84/#CVE-2026-84120
https://www.mozilla.org/en-US/security/advisories/mfsa2026-87/#CVE-2026-84120