CVE-2026-90272 perf: arm_pmuv3: Zero initialize hw_id branch stack field
A local attacker can read uninitialized kernel memory via the ARM PMU branch stack interface, potentially exposing sensitive data.
- 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-2026-90272?
CVE-2026-90272 is a vulnerability in Linux, published on 17 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:
perf: arm_pmuv3: Zero initialize hw_id branch stack field
PERF_SAMPLE_BRANCH_HW_INDEX is supported by BRBE so hw_id is passed to userspace, but it's never set by the BRBE driver. Zero initialize it as it should be according to the docs:
* For the architectures whose raw branch records are * already stored in age order, the hw_idx should be 0.
It's probably too risky to remove PERF_SAMPLE_BRANCH_HW_INDEX from BRBE now in case anyone is setting it and reading the value, but zero initializing the whole struct also protects against the same issue with new fields that are added in the future.
Which versions are affected by CVE-2026-90272?
How do I fix CVE-2026-90272?
Apply the vendor's patch.
Is CVE-2026-90272 being exploited?
There is no known exploitation of CVE-2026-90272 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-90272, DEBIAN-CVE-2026-90272, GHSA-8j89-gr3p-jpp8, UBUNTU-CVE-2026-90272.