How to fix CVE-2025-4086?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Monitor vendor channels for patch availability.

Is Firefox affected by CVE-2025-4086?

CVE-2025-4086 presents notable security risk rated CVSS 6.5. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

CVE-2025-4086

MEDIUM

2025-04-29 [email protected]

6.5

CVSS 3.1

CVSS Vector

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Patch Released

Apr 06, 2026 - 02:30 nvd

Patch available

Analysis Generated

Mar 28, 2026 - 18:39 vuln.today

CVE Published

Apr 29, 2025 - 14:15 nvd

MEDIUM 6.5

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.

Analysis

A specially crafted filename containing a large number of encoded newline characters could obscure the file's extension when displayed in the download dialog. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Technical Context

This vulnerability is classified under CWE-451. 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. Affected products include: Mozilla Firefox, Mozilla Thunderbird.

Affected Products

Mozilla Firefox, Mozilla Thunderbird.

Remediation

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.2

CVSS: +32

POC: 0

Vendor Status

CVE-2025-4086 vulnerability details – vuln.today

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CVE-2025-4086

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CVE-2025-4086

CVSS Vector

Lifecycle Timeline

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Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

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External POC / Exploit Code