Gradient, a nix‑based continuous integration system, has a flaw that allows anyone who can reach the /proto endpoint to register as a worker without credentials. The registration grants a session with PeerAuth::Open, which can read jobs from every organisation and write arbitrary store paths into nar_storage and the cached_path table. This permits malicious actors to poison the cache or write unexpected data, potentially leading to compromised builds or unauthorized code execution. The weakness is classified as authentication bypass (CWE‑306), cache poisoning (CWE‑345), and privilege escalation (CWE‑862).

The product affected is Gradient by wavelens, version 1.1.0. Users running this version should be aware that the default configuration enables the vulnerable discoverable mode (GRADIENT_DISCOVERABLE=true). No other product versions are known to be affected.

The vulnerability scores 9.4 on the CVSS scale, indicating a high‑severity risk. No EPSS score is available, and it is not listed in the CISA KEV catalog. The likely attack vector is remote network access to the /proto endpoint; an attacker does not need any prior authentication and can perform the exploit from any machine that can reach the service. The vulnerability was fixed in version 1.1.1, meaning the attack can be mitigated by upgrading or by disabling the discoverable mode.