{"id":"CVE-2026-103974","state":"PUBLISHED","title":"lichess.org: Stored HTML Injection via PGN Annotator Tag in Studies","description":"lichess.org is the forever free, adless and open source chess server. Prior to commit c54596c9e1569d378fe20f80d4c790c6fdee54c4, a user who can add a chapter to a study can place attacker-controlled text in the PGN Annotator tag, which becomes Comment.Author.External and is returned verbatim by authorText. When a study node has at least two comments, ui/analyse/src/treeView/inlineView.ts interpolates that author string into HTML passed to the innerHTML hook without escaping it. Opening the affected study can therefore render stored attacker-controlled HTML and CSS for other viewers, including navigation to an attacker-controlled site, content spoofing, and CSS-based data exposure, although the site's content security policy blocks injected JavaScript. This vulnerability is fixed by commit c54596c9e1569d378fe20f80d4c790c6fdee54c4.","publishedAt":"2026-10-14T18:17:13.770Z","updatedAt":"2026-10-14T19:41:15.577Z","severity":{"score":5.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["lichess-org lila"],"affected":[{"vendor":"lichess-org","product":"lila","versions":[{"version":"< c54596c9e1569d378fe20f80d4c790c6fdee54c4","status":"affected"}]}],"references":["https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","https://github.com/lichess-org/lila/commit/c54596c9e1569d378fe20f80d4c790c6fdee54c4"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/103xxx/CVE-2026-103974.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-103974","state":"PUBLISHED","datePublished":"2026-10-14T18:17:13.770Z","dateUpdated":"2026-10-14T19:41:15.577Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-01T16:09:08.456Z"},"containers":{"cna":{"title":"lichess.org: Stored HTML Injection via PGN Annotator Tag in Studies","descriptions":[{"lang":"en","value":"lichess.org is the forever free, adless and open source chess server. Prior to commit c54596c9e1569d378fe20f80d4c790c6fdee54c4, a user who can add a chapter to a study can place attacker-controlled text in the PGN Annotator tag, which becomes Comment.Author.External and is returned verbatim by authorText. When a study node has at least two comments, ui/analyse/src/treeView/inlineView.ts interpolates that author string into HTML passed to the innerHTML hook without escaping it. Opening the affected study can therefore render stored attacker-controlled HTML and CSS for other viewers, including navigation to an attacker-controlled site, content spoofing, and CSS-based data exposure, although the site's content security policy blocks injected JavaScript. This vulnerability is fixed by commit c54596c9e1569d378fe20f80d4c790c6fdee54c4."}],"affected":[{"vendor":"lichess-org","product":"lila","versions":[{"version":"< c54596c9e1569d378fe20f80d4c790c6fdee54c4","status":"affected"}]}],"references":[{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","name":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/lichess-org/lila/commit/c54596c9e1569d378fe20f80d4c790c6fdee54c4","name":"https://github.com/lichess-org/lila/commit/c54596c9e1569d378fe20f80d4c790c6fdee54c4","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-14T18:17:13.770Z"},"source":{"advisory":"GHSA-43g7-r6hp-ccf8","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-14T19:40:54.734332Z","id":"CVE-2026-103974","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-14T19:41:15.577Z"}}]}}}