This flaw occurs in the ALSA sequencer subsystem of the Linux kernel. The kernel’s native ioctl path for sequencer operations correctly serializes calls with a mutex, but the compatibility layer for 32‑bit port‑info ioctls bypasses this protection. Concurrent 32‑bit CREATE_PORT requests can therefore interleave, allowing an attacker to create more ports than the kernel believes exist. The computed index may wrap and reuse a freed port slot, leading the kernel to drop or interact with a stale subscriber. The result is an out‑of‑bounds access to memory that may corrupt kernel data structures or trigger a kernel panic. This can be leveraged to crash the system or potentially gain higher privileges if the attacker can control the freed data.

Based on the description, it is inferred that any Linux kernel build that includes the ALSA sequencer and supports 32‑bit compatibility IOCTLs is affected. No specific kernel version range is supplied in the available data, so any recent kernel that contains the vulnerable code until patched is potentially vulnerable.

The CVSS score of 4.7 indicates a moderate severity, and the EPSS score is below 1%, suggesting that exploitation opportunities are limited and likely not widespread. Although the flaw is not listed in CISA’s KEV catalogue, the race condition created by the missing mutex protection can still lead to a kernel crash or data corruption via a use‑after‑free in the ALSA sequencer. An attacker with local access and the ability to issue concurrent 32‑bit CREATE_PORT ioctls can trigger the out‑of‑bounds access. While the impact does not guarantee privilege escalation at this point, the ability to corrupt kernel memory or cause a crash poses a significant risk to system availability.