The Linux kernel contains a flaw in the vdpa_sim module where a valid ASID may be assigned to a group index that equals the number of groups, causing an out-of-bounds write. This memory corruption can overwrite kernel data structures. The underlying weakness is an out-of-bounds write (CWE‑787).

The vulnerability affects the Linux kernel for all released versions that have not incorporated the bound‑check patch referenced in commit 406db68f9cb976a8ddfafd631197264f2307e9c9. Any system running such a kernel and using the vdpa_sim interface, particularly within virtualized environments, is susceptible.

The CVSS score is 7.8, indicating high severity. The EPSS score is <1%, suggesting a very low exploitation probability, and the issue is not listed in the CISA KEV catalog. An out-of-bounds write in kernel space remains high‑severity. Based on the description, it is inferred that an attacker with local or privileged access capable of assigning an ASID to a group index equal to ngroups could trigger the vulnerability.