# CVE-2026-93138: bpf: Fix vmlinux BTF prep race in bpf_get_btf_vmlinux

> A race condition in Linux kernel BPF handling allows attackers to potentially execute arbitrary code or escalate privileges via memory corruption.

- **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-102888, BELL-CVE-2026-93138, DEBIAN-CVE-2026-93138, GHSA-j9m2-mp7m-3w46, UBUNTU-CVE-2026-93138

## What is CVE-2026-93138?

CVE-2026-93138 is a high-severity 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 vmlinux BTF prep race in bpf_get_btf_vmlinux

bpf_get_btf_vmlinux() lazily parses the vmlinux BTF under the
bpf_verifier_lock, but publishes the result through a plain store
and re-checks it through a plain lockless load. Nothing orders
the stores initializing the struct btf inside btf_parse_vmlinux()
against the store publishing the pointer: On a weakly ordered
arch, a concurrent first-time caller taking the lockless fast
path could in principle observe the pointer before the parsed
contents are visible. The mutex_unlock() does not help such a
reader given it only synchronizes with a later acquisition of the
same lock. Thus, publish the pointer with smp_store_release()
and read it on the fast path with smp_load_acquire().

Acquire semantics are needed rather than a dependency-ordered
READ_ONCE(): btf_parse_vmlinux() also populates globals outside
the returned object (e.g. bpf_ctx_convert.t). An address
dependency would only order accesses performed through the
pointer and not cover other globals.

## Which versions are affected by CVE-2026-93138?


## How do I fix CVE-2026-93138?

Apply the vendor's patch.

## Is CVE-2026-93138 being exploited?

There is no known exploitation of CVE-2026-93138 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93138 and fix it if it is affected.

What it is: CVE-2026-93138 is a high-severity 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-2026-93138 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-2026-93138/ (Markdown: https://insights.sbomify.com/CVE-2026-93138/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93138
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93138
- OSV: https://osv.dev/vulnerability/CVE-2026-93138

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93138/
Summaries are generated and may contain mistakes; the official description above is the record.