Trilium Notes is an open-source, cross-platform hierarchical note taking application with focus on building large personal knowledge bases. Prior to 0.101.0, a critical timing attack vulnerability in Trilium's sync authentication endpoint allows unauthenticated remote attackers to recover HMAC authentication hashes byte-by-byte through statistical timing analysis. This enables complete authentication bypass without password knowledge, granting full read/write access to victim's knowledge base. This vulnerability is fixed in 0.101.0.