# CVE-2026-97587: perf: RISC-V: store available counter mask as bitmap

> A local attacker can exploit a buffer overflow in the RISC-V perf subsystem to execute arbitrary code or escalate privileges.

- **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:** 25 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-104166, BELL-CVE-2026-97587, DEBIAN-CVE-2026-97587, GHSA-5mgm-fggv-mx2j, UBUNTU-CVE-2026-97587

## What is CVE-2026-97587?

CVE-2026-97587 is a memory corruption vulnerability in Linux, published on 25 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: RISC-V: store available counter mask as bitmap

The available-counter mask was a single unsigned long, but iteration
uses RISCV_MAX_COUNTERS, which is 64. On RV32 that reads past the object.
Filling with an unsigned-long bit at index 32 and above is also wrong.

Use DECLARE_BITMAP and set_bit/bitmap helpers. Walk each bitmap word
into CFG_MATCH when checking events, when allocating an index, and when
stopping all counters. Set the counter base to i times BITS_PER_LONG.
Share the CFG_MATCH ecall through a small helper so the 32-bit argument
split is not duplicated. On qemu-system-riscv32 the probe bitmap has bits
above XLEN set, so the first word alone is not enough.

[pjw@kernel.org: updated to apply; fixed checkpatch.pl issues]

## Which versions are affected by CVE-2026-97587?


## How do I fix CVE-2026-97587?

Apply the vendor's patch.

## Is CVE-2026-97587 being exploited?

There is no known exploitation of CVE-2026-97587 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97587 and fix it if it is affected.

What it is: CVE-2026-97587 is a memory corruption vulnerability in Linux, published on 25 Sep 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-2026-97587 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-2026-97587/ (Markdown: https://insights.sbomify.com/CVE-2026-97587/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97587
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97587
- OSV: https://osv.dev/vulnerability/CVE-2026-97587

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97587/
Summaries are generated and may contain mistakes; the official description above is the record.