An in‑kernel ChaCha implementation stored a temporary variable, permuted_state, on the stack, and failed to overwrite it before it went out of scope. Because the ChaCha permutation is reversible, an attacker who can read the kernel stack can recover the original state and thus the encryption key. The resulting key disclosure compromises all cryptographic operations that rely on ChaCha, including random number generation and authenticated encryption. This flaw represents a classic secret memory disclosure.

All Linux kernel versions that include the vulnerable ChaCha implementation, until the security patch is applied. The vulnerability is present in the kernel’s crypto subsystem across all distributions that ship an unpatched kernel.

With a CVSS score of 7.5, the flaw carries a high confidentiality impact. Based on the description, it is inferred that an attacker would need the ability to inspect kernel memory, such as through local privilege escalation or a kernel‑level payload, to recover encryption keys. No public exploit is known, and the EPSS score indicates a very low probability of exploitation (< 1 %). However, given that the vulnerability exposes critical cryptographic material, the risk is considered high. The vulnerability is not currently listed in the CISA KEV catalog, but it should be treated as a serious flaw due to its direct key‑compromise potential.