{"id":"CVE-2025-1935","title":"A web page could trick a user into setting that site as the default handler for a custom URL protocol","summary":"A web page could trick a user into setting that site as the default handler for a custom URL protocol. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N","cwe":["CWE-79"],"vendor":"mozilla","product":"firefox","affected":["firefox < 128.8.0","firefox < 136.0","thunderbird < 128.8.0","thunderbird >= 129.0, < 136.0"],"patched":["firefox 136.0","thunderbird 136.0"],"published":"2025-03-04","updated":"2026-09-30","sourceUpdated":"2026-09-30T19:10:01.007","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-1935","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1866661","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-14/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-16/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-17/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-18/","label":"security@mozilla.org"},{"url":"https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00343,"epssPercentile":0.25336,"ingestedAt":"2026-09-30T19:21:07.228Z","slug":"CVE-2025-1935","body":"## Overview\n\nA web page could trick a user into setting that site as the default handler for a custom URL protocol. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.\n\n## Affected\n\n- `firefox < 128.8.0`\n- `firefox < 136.0`\n- `thunderbird < 128.8.0`\n- `thunderbird >= 129.0, < 136.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `firefox 136.0`\n- `thunderbird 136.0`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}