# CVE-2026-90317: bpf: Invalidate RCU pointers after final spin unlock

> A use-after-free in the Linux kernel BPF subsystem allows attackers to trigger memory corruption and potentially execute code or escalate privileges.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102240, BELL-CVE-2026-90317, DEBIAN-CVE-2026-90317, GHSA-6jx2-qmxh-94v4, UBUNTU-CVE-2026-90317

## What is CVE-2026-90317?

CVE-2026-90317 is a high-severity use after free 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:

bpf: Invalidate RCU pointers after final spin unlock

In a sleepable BPF program, a spin lock can provide the only RCU protection
for a kptr. The final bpf_spin_unlock() ends that protection, but the
verifier leaves the pointer valid. Another CPU can then free the object
before the pointer is used. A capability-limited runtime PoC triggered a
task_struct use-after-free in __bpf_get_task_stack().

Record whether the program is in an RCU-protected context before releasing
the lock. Invalidate RCU-protected pointers only when the unlock leaves the
final such context. This preserves valid pointers in non-sleepable programs
and inside an explicit RCU read-side section.

## Which versions are affected by CVE-2026-90317?


## How do I fix CVE-2026-90317?

Apply the vendor's patch.

## Is CVE-2026-90317 being exploited?

There is no known exploitation of CVE-2026-90317 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90317 and fix it if it is affected.

What it is: CVE-2026-90317 is a high-severity use after free 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.
Exploitation: There is no known exploitation of CVE-2026-90317 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-2026-90317/ (Markdown: https://insights.sbomify.com/CVE-2026-90317/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90317
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90317
- OSV: https://osv.dev/vulnerability/CVE-2026-90317

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90317/
Summaries are generated and may contain mistakes; the official description above is the record.