CVE-2026-103974

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...

CVE-2026-103974 lichess.org: Stored HTML Injection via PGN Annotator Tag in Studies

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...

CVE-2026-103974

The chess server lichess.org is vulnerable to Stored HTML Injection in its study features. An attacker who can add a chapter to a study can place malicious text within the PGN Annotator tag , which is then stored as Comment.Author.External. When a study node contains at least two comments, the fi...