Vulnerability · Published Sep 15, 2026 · Assigned by mozilla
CVE-2026-92238Ambiguous parsing of mail headers
Critical 9.8
In plain English
A critical-severity security flaw 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 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.5%top 54.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. 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-2026-92238 |
| Debian:13 | thunderbird | 1:140.16.0esr-1~deb13u1 | DEBIAN-CVE-2026-92238 |
| Debian:14 | thunderbird | 1:153.3.0esr-1 | DEBIAN-CVE-2026-92238 |
| 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-2026-92238 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-92238 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-92238 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-92238 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-92238 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-92238 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | see references |
Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H