CVE-2025-4086 — User Interface (UI) Misrepresentation of Critical Information in Mozilla Firefox

CWE-451 — User Interface (UI) Misrepresentation of Critical Information8 documents7 sources
Severity
6.5MEDIUMNVD
EPSS
0.2%
top 52.50%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla FirefoxMozilla Thunderbird
Timeline
PublishedApr 29

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 was fixed in Firefox 138 and Thunderbird 138.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitability: 3.9 | Impact: 2.5

Affected Packages2 packages

▶NVDmozilla/thunderbird< 138.0
▶NVDmozilla/firefox< 138.0

🔴Vulnerability Details

3
OSV
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↗2025-04-29
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GHSA
GHSA-54jr-pmx4-5pvr: A specially crafted filename containing a large number of encoded newline characters could obscure the file's extension when displayed in the download↗2025-04-29
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CVEList
Specially crafted filename could be used to obscure download type↗2025-04-29
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📋Vendor Advisories

4
Red Hat
firefox: thunderbird: Specially crafted filename could be used to obscure download type↗2025-04-29
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Debian
CVE-2025-4086: firefox - A specially crafted filename containing a large number of encoded newline charac...↗2025
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Mozilla
Mozilla Foundation Security Advisory 2025-31: CVE-2025-4086↗
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Mozilla
Mozilla Foundation Security Advisory 2025-28: CVE-2025-4086↗
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CVE-2025-4086 — Mozilla Firefox vulnerability | cvebase