Vulnerability · Published Sep 15, 2026 · Assigned by mozilla
CVE-2026-92240Out-of-bounds read in IMAP response parser
Critical 9.1
In plain English
A critical-severity out-of-bounds read in Thunderbird from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A malicious or compromised IMAP server can trigger an out-of-bounds read in the IMAP response parser by sending an untagged '* ID' response, crashing Thunderbird. The affected parsing path is reachable before authentication. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | thunderbird | 140.16.0-1.el10_2.alma.1 | ALSA-2026:73130 |
| AlmaLinux:8 | thunderbird | 140.16.0-1.el8_10.alma.1 | ALSA-2026:73971 |
| AlmaLinux:9 | thunderbird | 140.16.0-1.el9_8.alma.1 | ALSA-2026:70642 |
| Debian:12 | thunderbird | 1:140.16.0esr-1~deb12u1 | DEBIAN-CVE-2026-92240 |
| Debian:13 | thunderbird | 1:140.16.0esr-1~deb13u1 | DEBIAN-CVE-2026-92240 |
| Debian:14 | thunderbird | 1:153.3.0esr-1 | DEBIAN-CVE-2026-92240 |
| Rocky Linux:10 | thunderbird | 0:140.16.0-1.el10_2 | RLSA-2026:73130 |
| Rocky Linux:8 | thunderbird | 0:140.16.0-1.el8_10 | RLSA-2026:73971 |
| Rocky Linux:9 | thunderbird | 0:140.16.0-1.el9_8 | RLSA-2026:70642 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-92240 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-92240 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-92240 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-92240 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-92240 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-92240 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | see references |
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H