{"id":"CVE-2026-103974","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-103974","generatedAt":"2026-10-28T01:12:12.678Z","title":"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.","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.","published":"2026-10-14T19:17:08.000Z","lastModified":"2026-10-16T20:04:30.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":5.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"},"cwe":["CWE-79"],"affected":[],"epss":{"score":0.00214,"percentile":0.1171,"date":"2026-10-26","history":[{"date":"2026-10-15","score":0.00214,"percentile":0.10995}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-14T19:17:08.000Z","detail":{"score":"5.4","severity":"MEDIUM","publishedAt":"2026-10-14T19:17:07.843Z"},"summary":"New CVE, medium severity (CVSS 5.4)."}],"references":[{"url":"https://github.com/lichess-org/lila/commit/c54596c9e1569d378fe20f80d4c790c6fdee54c4","source":"security-advisories@github.com"},{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","source":"security-advisories@github.com"},{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-103974","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}