{"id":"CVE-2025-5266","title":"Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks","summary":"Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.","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-200"],"vendor":"mozilla","product":"firefox","affected":["firefox < 128.11.0","firefox < 139.0"],"patched":["firefox 139.0"],"published":"2025-05-27","updated":"2026-09-30","sourceUpdated":"2026-09-30T18:10:00.190","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-5266","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1965628","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-42/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-44/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-45/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-46/","label":"security@mozilla.org"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00327,"epssPercentile":0.23343,"ingestedAt":"2026-09-30T18:17:24.439Z","slug":"CVE-2025-5266","body":"## Overview\n\nScript elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.\n\n## Affected\n\n- `firefox < 128.11.0`\n- `firefox < 139.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `firefox 139.0`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}