CVE-2025-3523: Mozilla Thunderbird · CWE-451
Affects Mozilla ThunderbirdSource CVE Database V5
Not known to be exploited · CVSS 6.4 Medium : upgrade to 137.0.2 or 128.9.2 when convenient.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 137.0.2, 128.9.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:LExploitation evidence
Disclosed: evidence found.
CVE published 15 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 26 Oct 2026.
What to do
Upgrade Mozilla Thunderbird to 137.0.2 or 128.9.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Thunderbird | Affected
| Fixed in
|
AI-suggested
This vulnerability has been fixed by Mozilla in Thunderbird 137.0.2 and Thunderbird ESR 128.9.2. Users and administrators should update to these versions or later to remediate the issue. No additional mitigation steps are required as the fix is officially available.
Description
When an email contains multiple attachments with external links via the X-Mozilla-External-Attachment-URL header, only the last link is shown when hovering over any attachment. Although the correct link is used on click, the misleading hover text could trick users into downloading content from untrusted sources. This vulnerability was fixed in Thunderbird 137.0.2 and Thunderbird 128.9.2.