CVE-2026-61500

CVE-2026-61500 describes a vulnerability affecting Rejetto HFS versions 3.0.0 through 3.2.0. The flaw stems from the application's use of the non-cryptographic `Math.random()` generator to create session-cookie signing keys. Additionally, outputs from this same generator are disclosed to unauthenticated clients during the login process. A remote attacker can exploit this by collecting a small number of login responses to reconstruct the state of the `Math.random()` generator. This allows them to recover the session-cookie signing key and subsequently forge a valid administrator session cookie. With a forged administrator session, an attacker can gain full administrative access and achieve remote code execution via the `server_code` configuration feature.