A flaw in Linux kernel’s authencesn crypto routine writes high‑order sequence bits to the destination buffer during out‑of‑place decryption, even though those bits could be copied directly from the source. This mis‑behaviour represents a CWE‑237 weakness and causes the data that is subsequently hashed to differ from the actual plaintext, potentially corrupting cryptographic results. The adverse outcome is that authentication or integrity checks that rely on the hash may produce incorrect outcomes, which could be exploited to bypass or undermine security controls.

The vulnerability resides in the authencesn cryptographic routine of the Linux kernel. Any kernel version that does not yet include the patch that removes the unnecessary write to the destination buffer is potentially exposed. The affected version information is not explicitly listed, so all releases prior to the fix should be considered at risk.

The CVSS score is 7.8 and the EPSS score is less than 1%, and the flaw is not listed in the CISA KEV catalog. Based on the description, it is inferred that an attacker would need to supply crafted input to the kernel’s authencesn decryption function in order to influence the hashing operation; such input would likely require kernel‑level access or the ability to control kernel memory. No publicly available exploit has been reported, and the low EPSS suggests a low probability of real‑world exploitation, but the inherent error in cryptographic handling warrants cautious assessment.