CVE-2025-4086

Description

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 affects Firefox < 138 and Thunderbird < 138.

Category

6.5
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.04%
Vendor Advisory mozilla.org Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Affected: Mozilla Thunderbird
Published at:
Updated at:

References

Link Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1945705 permissions required
https://www.mozilla.org/security/advisories/mfsa2025-28/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2025-31/ vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-4086?
CVE-2025-4086 has been scored as a medium severity vulnerability.
How to fix CVE-2025-4086?
To fix CVE-2025-4086, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-4086 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-4086 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-4086?
CVE-2025-4086 affects Mozilla Firefox, Mozilla Thunderbird.
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