| Name | CVE-2026-4371 |
| Description | A malicious mail server could send malformed strings with negative lengths, causing the parser to read memory outside the buffer. If a mail server or connection to a mail server were compromised, an attacker could cause the parser to malfunction, potentially crashing Thunderbird or leaking sensitive data. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9. |
| 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-4511-1, DSA-6179-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| thunderbird (PTS) | bullseye | 1:115.12.0-1~deb11u1 | vulnerable |
| bullseye (security) | 1:140.9.1esr-1~deb11u1 | fixed | |
| bookworm | 1:140.6.0esr-1~deb12u1 | vulnerable | |
| bookworm (security) | 1:140.9.1esr-1~deb12u1 | fixed | |
| trixie | 1:140.8.0esr-1~deb13u1 | vulnerable | |
| trixie (security) | 1:140.9.1esr-1~deb13u1 | fixed | |
| forky | 1:140.9.0esr-1 | fixed | |
| sid | 1:140.9.1esr-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| thunderbird | source | bullseye | 1:140.9.0esr-1~deb11u1 | DLA-4511-1 | ||
| thunderbird | source | bookworm | 1:140.9.0esr-1~deb12u1 | DSA-6179-1 | ||
| thunderbird | source | trixie | 1:140.9.0esr-1~deb13u1 | DSA-6179-1 | ||
| thunderbird | source | (unstable) | 1:140.9.0esr-1 |
https://www.mozilla.org/en-US/security/advisories/mfsa2026-24/#CVE-2026-4371