CVE-2025-6433

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{"bugzilla": {"description": "firefox: WebAuthn would allow a user to sign a challenge on a webpage with an invalid TLS certificate", "id": "2374567", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2374567"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N", "status": "draft"}, "details": ["If a user visited a webpage with an invalid TLS certificate, and granted an exception, the webpage was able to provide a WebAuthn challenge that the user would be prompted to complete. This is in violation of the WebAuthN spec which requires \"a secure transport established without errors\". This vulnerability affects Firefox < 140."], "name": "CVE-2025-6433", "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": "rhel10/firefox-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "firefox", "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:8", "fix_state": "Not affected", "package_name": "firefox", "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"}], "public_date": "2025-06-24T12:28:04Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-6433\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-6433\nhttps://bugzilla.mozilla.org/show_bug.cgi?id=1954033\nhttps://www.mozilla.org/security/advisories/mfsa2025-51/"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Low"}

{"analysis": {"en": {"generated_at": "2026-04-20T16:57:41.030688+00:00", "value": {"mitigation_remediation": ["Update Mozilla Firefox to version 140 or later.", "Update Mozilla Thunderbird to version 140 or later.", "Configure the browsers to refuse connections with invalid TLS certificates and avoid accepting exceptions on unexpected sites."], "summary": {"action": "Immediate Patch", "impact": "Unauthorized Signing of WebAuthn Challenges via Invalid TLS"}, "threat_synthesis": {"affected_systems": "This flaw affects Mozilla Firefox and Mozilla Thunderbird versions prior to 140. Upgrades to Firefox 140+ or Thunderbird 140+ contain the fix. These products are the sole vendors identified, as listed in the CVE data.", "description_and_impact": "The vulnerability permits a webpage served over an invalid TLS connection to provide a WebAuthn challenge that the user can sign, which contravenes the WebAuthn specification that mandates a securely established transport. An attacker could therefore coerce a user into signing arbitrary data or authentication assertions, potentially enabling credential theft or unauthorized access. This isolation of a secure channel is a significant break in the web authentication model.", "risk_and_exploitability": "With a CVSS score of 9.8 the vulnerability is high severity, but its EPSS score of less than 1% indicates a low probability of exploitation at present, and it is not listed in CISA KEV. The expected attack vector requires a user to accept an invalid certificate and then interact with a webpage that presents a WebAuthn challenge; an attacker performing a phishing campaign could exploit this, though significant user interaction is required. Protective measures are recommended to reduce risk until the patch is applied."}}}}, "created": "2025-07-06T22:16:29.563900+00:00", "updated": "2026-04-20T17:00:12.760099+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}