# CVE-2026-72237: perf/x86/amd/brs: Fix kernel address leakage

> Local attackers can leak kernel memory addresses via AMD BRS branch records, bypassing user-space filtering restrictions.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-72237, DEBIAN-CVE-2026-72237, GHSA-wcfv-p978-69xf, UBUNTU-CVE-2026-72237

## What is CVE-2026-72237?

CVE-2026-72237 is a vulnerability in Linux, published on 15 Aug 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/x86/amd/brs: Fix kernel address leakage

A user-only branch stack can contain branches that originate from
the kernel. As a result, kernel addresses are exposed to user space
even when PERF_SAMPLE_BRANCH_USER is requested. On AMD processors
supporting X86_FEATURE_BRS (Zen 3 only), perf can still report entries
such as SYSRET/interrupt returns for which the branch-from addresses
are in the kernel.

E.g.

  $ perf record -j any,u -c 4000 -e branch-brs -o - -- \
        perf bench syscall basic --loop 1000 | \
        perf script -i - -F brstack|tr ' ' '\n'| \
        grep -E '0x[89a-f][0-9a-f]{15}'

  ...
  0xffffffff810001c4/0x72e2e32955eb/-/-/-/0//-
  0xffffffff810001c4/0x72e2d94a9821/-/-/-/0//-
  0xffffffff810001c4/0x72e2d94ffa1b/-/-/-/0//-
  ...

BRS provides no hardware branch filtering, so privilege level
filtering is performed entirely in software. However, amd_brs_match_plm()
only validates the branch-to address against the requested privilege
levels. For branches from the kernel to user space, the branch-from
address is left unchecked and is leaked. Extend the software filter to
also validate the branch-from address, so that any branch record whose
branch-from address is in the kernel is dropped when
PERF_SAMPLE_BRANCH_USER is requested.

## Which versions are affected by CVE-2026-72237?


## How do I fix CVE-2026-72237?

Apply the vendor's patch.

## Is CVE-2026-72237 being exploited?

There is no known exploitation of CVE-2026-72237 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72237 and fix it if it is affected.

What it is: CVE-2026-72237 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72237 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72237/ (Markdown: https://insights.sbomify.com/CVE-2026-72237/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72237
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72237
- OSV: https://osv.dev/vulnerability/CVE-2026-72237

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72237/
Summaries are generated and may contain mistakes; the official description above is the record.