{"id":"CVE-2026-100803","state":"PUBLISHED","title":"Same-origin policy bypass in the WebExtensions component","description":"Same-origin policy bypass in the WebExtensions component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.","publishedAt":"2026-09-29T12:36:20.195Z","updatedAt":"2026-10-01T15:16:27.751Z","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 Firefox","Mozilla Thunderbird"],"affected":[{"vendor":"Mozilla","product":"Firefox","versions":[{"version":"115.42","status":"unaffected","lessThanOrEqual":"115.*","versionType":"rpm"},{"version":"140.17","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.4","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"157","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]},{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"140.17","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.4","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"157","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":["https://bugzilla.mozilla.org/show_bug.cgi?id=2057988","https://www.mozilla.org/security/advisories/mfsa2026-100/","https://www.mozilla.org/security/advisories/mfsa2026-101/","https://www.mozilla.org/security/advisories/mfsa2026-102/","https://www.mozilla.org/security/advisories/mfsa2026-103/","https://www.mozilla.org/security/advisories/mfsa2026-97/","https://www.mozilla.org/security/advisories/mfsa2026-98/","https://www.mozilla.org/security/advisories/mfsa2026-99/"],"weaknesses":["CWE-346"],"ingestedAt":"2026-10-29T20:10:13.529Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/100xxx/CVE-2026-100803.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-100803","state":"PUBLISHED","datePublished":"2026-09-29T12:36:20.195Z","dateUpdated":"2026-10-01T15:16:27.751Z","assignerShortName":"mozilla","assignerOrgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateReserved":"2026-09-26T19:17:51.124Z"},"containers":{"cna":{"title":"Same-origin policy bypass in the WebExtensions component","descriptions":[{"lang":"en","value":"Same-origin policy bypass in the WebExtensions component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17."}],"affected":[{"vendor":"Mozilla","product":"Firefox","versions":[{"version":"115.42","status":"unaffected","lessThanOrEqual":"115.*","versionType":"rpm"},{"version":"140.17","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.4","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"157","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]},{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"140.17","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.4","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"157","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2057988"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-100/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-101/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-102/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-103/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-97/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-98/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-99/"}],"providerMetadata":{"shortName":"mozilla","orgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateUpdated":"2026-09-30T17:20:42.279Z"},"credits":[{"lang":"en","value":"Yaqoub Aldurayhim"}]},"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":{"timestamp":"2026-10-01T15:15:51.082535Z","id":"CVE-2026-100803","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-346","type":"CWE","lang":"en","description":"CWE-346 Origin Validation Error"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-01T15:16:27.751Z"}}]}}}