CVE-2025-4086

6.5 MEDIUM 0.3% exploit odds Fix listed Disclosure Browser & mail

What it is

A specially crafted filename containing a large number of encoded newline characters could obscure the file's extension when displayed in the download dialog. *This bug only affects Thunderbird for Android. Other versions of Thunderbird are unaffected.*. This vulnerability was fixed in Firefox 138 and Thunderbird 138.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 0.3% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-04-29 14:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-09-30 18:10 UTC Last updatedMost recent change to the record

Details

Published: 2025-04-29 14:15 UTC
Last modified: 2026-09-30 18:10 UTC
Exploit probability: 0.3% · EPSS, next 30 days
Weakness: CWE-451
Record status: Modified

Affected

Mozilla Firefox < 138.0
Mozilla Thunderbird < 138.0

Attack profile CVSS 3.1 · 6.5

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record