{"id":"CVE-2025-3909","state":"PUBLISHED","title":"JavaScript Execution via Spoofed PDF Attachment and file:/// Link","description":"Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.","publishedAt":"2025-05-14T16:56:43.630Z","updatedAt":"2026-04-13T14:27:53.020Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","source":"CISA-ADP"},"assigner":"mozilla","products":["Mozilla Thunderbird"],"affected":[{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"128.10.1","status":"unaffected","lessThanOrEqual":"128.*","versionType":"rpm"},{"version":"138.0.1","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":["https://bugzilla.mozilla.org/show_bug.cgi?id=1958376","https://www.mozilla.org/security/advisories/mfsa2025-34/","https://www.mozilla.org/security/advisories/mfsa2025-35/","https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html"],"weaknesses":["CWE-356"],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/3xxx/CVE-2025-3909.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-3909","state":"PUBLISHED","datePublished":"2025-05-14T16:56:43.630Z","dateUpdated":"2026-04-13T14:27:53.020Z","assignerShortName":"mozilla","assignerOrgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateReserved":"2025-04-23T17:44:42.650Z"},"containers":{"cna":{"title":"JavaScript Execution via Spoofed PDF Attachment and file:/// Link","descriptions":[{"lang":"en","value":"Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1."}],"affected":[{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"128.10.1","status":"unaffected","lessThanOrEqual":"128.*","versionType":"rpm"},{"version":"138.0.1","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1958376"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-34/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-35/"}],"providerMetadata":{"shortName":"mozilla","orgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateUpdated":"2026-04-13T14:27:53.020Z"},"credits":[{"lang":"en","value":"Dario Weißer"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":8.1,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","integrityImpact":"HIGH","userInteraction":"REQUIRED","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"id":"CVE-2025-3909","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2025-05-16T03:55:44.016748Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-356","lang":"en","type":"CWE","description":"CWE-356 Product UI does not Warn User of Unsafe Actions"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-02-26T18:28:09.659Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T19:58:39.208Z"}}]}}}