CVE-2025-4086

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.
UI
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTNIST
6.5 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
mozillaCNA
---
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CISA-ADPADP
6.5 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 11%
VendorProductVersion
mozillafirefox
𝑥
< 138.0
mozillathunderbird
𝑥
< 138.0
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
139.0-1
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
firefox
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
not-affected
focal
not-affected
thunderbird
plucky
not-affected
oracular
not-affected
noble
not-affected
jammy
not-affected
focal
not-affected
Common Weakness Enumeration
Vulnerability Media Exposure
References
https://bugzilla.mozilla.org/show_bug.cgi?id=1945705
https://www.mozilla.org/security/advisories/mfsa2025-28/
https://www.mozilla.org/security/advisories/mfsa2025-31/