CVE-2026-89443 platform/x86: ISST: Validate level in perf mask ioctls
A missing bounds check in the Linux kernel ISST driver allows local attackers to trigger out-of-bounds reads via crafted ioctl calls, potentially leaking memory or causing crashes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89443?
CVE-2026-89443 is a high-severity memory corruption vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
platform/x86: ISST: Validate level in perf mask ioctls
isst_if_get_perf_level_mask() and isst_if_get_base_freq_mask() use the user-provided level as an index into perf_levels[] via _read_pp_level_info() and _read_bf_level_info(), but neither helper validates it first.
The adjacent level-info helpers reject levels above max_level before reading the same per-level register block. Add the same bounds checks to the mask helpers, and reject disabled SST-PP levels in isst_if_get_perf_level_mask() to match isst_if_get_perf_level_info().
This prevents out-of-bounds reads from the per-level offset table on invalid ioctl input.
Which versions are affected by CVE-2026-89443?
How do I fix CVE-2026-89443?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89443 being exploited?
There is no known exploitation of CVE-2026-89443 in the wild and no public exploit code.
Sources
Also known as AZL-100518, BELL-CVE-2026-89443, DEBIAN-CVE-2026-89443, GHSA-5hf2-3p4g-qfhr, UBUNTU-CVE-2026-89443.