CVE-2026-54617: LaunchServer FileServerHandler has an unauthenticated path traversal issue

An unauthenticated path traversal in the LaunchServer HTTP file server (FileServerHandler) lets any remote actor read any file readable by the LaunchServer process (e.g. ../../../../etc/passwd). This is a generic arbitrary-file-read primitive, so the fix must address the traversal itself, not any specific file.

The readable files include the server’s own secrets, which turns this from information disclosure into full compromise: the ECDSA private key that signs access JWTs (.keys/ecdsa_id), the refresh-token salt (.keys/legacySalt), and LaunchServer.json (database credentials). With the signing key an attacker mints a valid access token for any account, including admins. That is a full authentication bypass. Pre-auth, default config, port 9274.

Affected: GravitLauncher LaunchServer ≤ 5.7.11 (the LaunchServer application; the published pro.gravit.launcher:*-api Maven artifacts do not contain the vulnerable code).