{"id":"CVE-2026-103974","title":"lichess.org is the forever free, adless and open source chess server","summary":"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 be…","severity":"medium","cvss":5.4,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","cwe":["CWE-79"],"published":"2026-10-14","updated":"2026-10-14","sourceUpdated":"2026-10-14T20:17:29.167","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-103974","references":[{"url":"https://github.com/lichess-org/lila/commit/c54596c9e1569d378fe20f80d4c790c6fdee54c4","label":"security-advisories@github.com"},{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","label":"security-advisories@github.com"},{"url":"https://github.com/lichess-org/lila/security/advisories/GHSA-43g7-r6hp-ccf8","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"ingestedAt":"2026-10-14T19:49:57.605Z","vendor":"lichess-org","product":"lila","affected":["lila < c54596c9e1569d378fe20f80d4c790c6fdee54c4"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-14T19:40:54.734332Z"},"slug":"CVE-2026-103974","body":"## Overview\n\nlichess.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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":29.7,"likelihood":0,"exploitation":12,"ransomware":0},"changes":[{"seq":221885,"id":"CVE-2026-103974","ts":1792035893847,"field":"exploit_available","old":"false","new":"true"}]}