CVE-2025-4086

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{"bugzilla": {"description": "firefox: thunderbird: Specially crafted filename could be used to obscure download type", "id": "2362914", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2362914"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-451", "details": ["A specially crafted filename containing a large number of encoded newline characters could obscure the file's extension when displayed in the download dialog.\n*This bug only affects Thunderbird for Android. Other versions of Thunderbird are unaffected.* This vulnerability affects Firefox < 138 and Thunderbird < 138.", "A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue: 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 Firefox for Android. Other versions of Firefox are unaffected."], "name": "CVE-2025-4086", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "firefox-flatpak-container", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "thunderbird-flatpak-container", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "firefox-flatpak-container", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "thunderbird-flatpak-container", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-29T13:13:40Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-4086\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-4086\nhttps://bugzilla.mozilla.org/show_bug.cgi?id=1945705\nhttps://www.mozilla.org/security/advisories/mfsa2025-28/\nhttps://www.mozilla.org/security/advisories/mfsa2025-31/"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Moderate"}

{"analysis": {"en": {"generated_at": "2026-04-21T21:04:23.913497+00:00", "value": {"mitigation_remediation": ["Upgrade Thunderbird for Android to version 138 or later.", "Avoid downloading files from untrusted or unknown sources until the update is installed and verify file extensions before opening.", "Use a reputable antivirus or malware detection tool to scan downloaded files for suspicious extensions before execution."], "summary": {"action": "Patch Immediately", "impact": "File type obfuscation that could lead to malicious files being executed"}, "threat_synthesis": {"affected_systems": "Mozilla Thunderbird for Android is affected; other Thunderbird versions are unaffected. Firefox is not impacted. The issue was fixed in Thunderbird version 138, so any installation prior to that applies.", "description_and_impact": "A specially crafted filename containing numerous encoded newline characters can hide the true file extension from the download dialog, making it appear as a safe type. The malicious file may deceive users into trusting or executing it, thus compromising system integrity and potentially leading to malware execution.", "risk_and_exploitability": "The CVSS score of 6.5 indicates moderate severity, and the EPSS score of under 1% shows a low probability of exploitation. Exploitation requires user interaction: a malicious actor must provide a file with an encoded-newline payload that the user downloads, and the file must be opened or executed on the device. The attack vector is inferred to be social engineering through downloads from potentially untrusted sources."}}}}, "created": "2026-04-21T21:15:45.445300+00:00", "updated": "2026-04-21T21:15:45.445310+00:00", "vendors": []}