Vulnerability · Published Mar 24, 2026 · Assigned by mozilla
CVE-2026-3889Spoofing issue in Thunderbird
Medium 6.5
In plain English
A medium-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 0.2% (higher than 11% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.2%top 89.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | thunderbird | 140.9.0-1.el10_1.alma.1 | ALSA-2026:6342 |
| AlmaLinux:8 | thunderbird | 140.9.0-1.el8_10.alma.1 | ALSA-2026:6917 |
| AlmaLinux:9 | thunderbird | 140.9.0-1.el9_7.alma.1 | ALSA-2026:6188 |
| Debian:12 | thunderbird | 1:140.9.0esr-1~deb12u1 | DEBIAN-CVE-2026-3889 |
| Debian:12 | thunderbird | 1:140.9.0esr-1~deb12u1 | DSA-6179-1 |
| Debian:13 | thunderbird | 1:140.9.0esr-1~deb13u1 | DSA-6179-1 |
| Debian:13 | thunderbird | 1:140.9.0esr-1~deb13u1 | DEBIAN-CVE-2026-3889 |
| Debian:14 | thunderbird | 1:140.9.0esr-1 | DEBIAN-CVE-2026-3889 |
| Rocky Linux:10 | thunderbird | 0:140.9.0-1.el10_1 | RLSA-2026:6342 |
| Rocky Linux:8 | thunderbird | 0:140.9.0-1.el8_10 | RLSA-2026:6917 |
| Rocky Linux:9 | thunderbird | 0:140.9.0-1.el9_7 | RLSA-2026:6188 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-3889 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-3889 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-3889 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-3889 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-3889 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-3889 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | see references |
Weakness: CWE-451 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N