{"id":"CVE-2025-4087","title":"A vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access","summary":"A vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access. This could lead to out-of-bounds read access and potentially, memory corruption. This …","severity":"medium","cvss":4.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","cwe":["CWE-125"],"vendor":"mozilla","product":"firefox","affected":["firefox < 128.10","firefox < 138.0","thunderbird < 128.10.0","thunderbird < 138.0"],"patched":["firefox 138.0","thunderbird 138.0"],"published":"2025-04-29","updated":"2026-09-30","sourceUpdated":"2026-09-30T18:10:00.190","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-4087","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1952465","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-28/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-29/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-31/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-32/","label":"security@mozilla.org"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00024.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00317,"epssPercentile":0.2228,"ingestedAt":"2026-09-30T18:17:24.434Z","slug":"CVE-2025-4087","body":"## Overview\n\nA vulnerability was identified in Thunderbird where XPath parsing could trigger undefined behavior due to missing null checks during attribute access. This could lead to out-of-bounds read access and potentially, memory corruption. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Thunderbird 138, and Thunderbird 128.10.\n\n## Affected\n\n- `firefox < 128.10`\n- `firefox < 138.0`\n- `thunderbird < 128.10.0`\n- `thunderbird < 138.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `firefox 138.0`\n- `thunderbird 138.0`","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":26.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}