Skip to main content
VulnerabilityPublished Updated

CVE-2026-3889: Mozilla Thunderbird · CWE-451

Affects Mozilla ThunderbirdSource CVE Database V5

0
Compare

Not known to be exploited · CVSS 6.5 Medium · patch available : update Mozilla Thunderbird when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Mozilla ThunderbirdAffected
  • <140.9
Fixed in
  • 140.9

AI-suggested

Mozilla has released official fixes for this vulnerability in Thunderbird versions 149 and 140.9. Users should update to these versions to remediate the issue. The vendor advisory notes that no additional action is required beyond applying these updates. Since Thunderbird is not a cloud service, remediation depends on user-side patching. Patch status is confirmed by the Mozilla Foundation Security Advisories MFSA2026-23 and MFSA2026-24.

Description

Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.

References

Community reviews

Loading reviews…