A field‑spanning write occurs during RSI attestation token initialization, where a 64‑byte challenge is copied into an 8‑byte field. This results in an out‑of‑bounds write that may corrupt adjacent kernel data structures. The severity depends on how the corrupted data is subsequently used; the description does not confirm that the overwrite would directly lead to code execution, but it could potentially facilitate further exploitation or system instability. No explicit attacker control over the copy size or content is mentioned, so it is inferred that an attacker would need to trigger the vulnerable routine, possibly through a privileged guest or specialized hardware interaction. The issue corresponds to CWE‑787, an out‑of‑bounds write.

All arm64 Linux kernel builds that implement the RSI interface and have not yet incorporated the patch referenced in the commit history are affected. This includes any kernel version compiled from the mainline tree prior to the merge of the fix. The affected component is the RSI attestation token initialization code within the arm64 architecture layer. No specific version list is available, but systems derived from the mainline kernel before the patch commit are at risk.

The CVSS score is 5.5, and the EPSS score indicates a very low exploitation probability (<1%). The flaw is not listed in the CISA KEV catalog. The out‑of‑bounds write poses a kernel memory corruption risk. Exploitation would require the ability to invoke the rsi_attestation_token_init routine, which is likely tied to privileged or guest execution contexts. Until the kernel is updated, the risk is considered high for systems that expose the RSI interface and do not employ additional hardening such as KASLR, SMEK, or SMAP.