# CVE-2026-90210: bpf: Fix UAF in bpf_trampoline_multi_attach_free on update failure

> A use-after-free vulnerability in the Linux kernel's BPF trampoline handling allows attackers to potentially execute arbitrary 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:** GHSA-gj8p-gx9h-pwwh, UBUNTU-CVE-2026-90210

## What is CVE-2026-90210?

CVE-2026-90210 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: Fix UAF in bpf_trampoline_multi_attach_free on update failure

When bpf_trampoline_update() fails before modify_fentry_multi()/
unregister_fentry_multi() is called, cur_image is unchanged
(cur_image == old_image) and ftrace still calls into it.  Freeing
old_image in that case causes a UAF.

Only free old_image when it differs from cur_image.

## Which versions are affected by CVE-2026-90210?


## How do I fix CVE-2026-90210?

Apply the vendor's patch.

## Is CVE-2026-90210 being exploited?

There is no known exploitation of CVE-2026-90210 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90210 and fix it if it is affected.

What it is: CVE-2026-90210 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-2026-90210 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-2026-90210/ (Markdown: https://insights.sbomify.com/CVE-2026-90210/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90210
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90210
- OSV: https://osv.dev/vulnerability/CVE-2026-90210

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90210/
Summaries are generated and may contain mistakes; the official description above is the record.