# CVE-2026-98037: bpf: Reject untrusted allocated-object pointers

> A local attacker can exploit a use-after-free vulnerability in the Linux kernel BPF 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:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98037, DEBIAN-CVE-2026-98037, GHSA-3hhf-gmj4-q58c, UBUNTU-CVE-2026-98037

## What is CVE-2026-98037?

CVE-2026-98037 is an use after free 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:

bpf: Reject untrusted allocated-object pointers

When the final RCU read-side critical section ends, a local kptr is demoted
to PTR_UNTRUSTED but retains MEM_ALLOC. The pointer may be NULL or may refer
to an object whose lifetime is no longer protected.

type_is_ptr_alloc_obj() nevertheless recognizes any PTR_TO_BTF_ID with
MEM_ALLOC as a live allocated object. In particular, a refcount-only local
kptr never carries NON_OWN_REF, so it still passes the
bpf_refcount_acquire() argument check after RCU protection ends. The kfunc
can then dereference NULL or stale memory.

Make type_is_ptr_alloc_obj() reject PTR_UNTRUSTED pointers. Since
type_is_non_owning_ref() is based on the same predicate, graph kfunc
arguments obey the same live-object requirement. Fault-protected reads of
the demoted pointer remain valid: writes are already rejected, and read
fixups use bpf_may_fault_on_deref() rather than this predicate.

[ kkd: Rewrote commit log ]

## Which versions are affected by CVE-2026-98037?


## How do I fix CVE-2026-98037?

Apply the vendor's patch.

## Is CVE-2026-98037 being exploited?

There is no known exploitation of CVE-2026-98037 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98037 and fix it if it is affected.

What it is: CVE-2026-98037 is an use after free 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-2026-98037 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-2026-98037/ (Markdown: https://insights.sbomify.com/CVE-2026-98037/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98037
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98037
- OSV: https://osv.dev/vulnerability/CVE-2026-98037

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98037/
Summaries are generated and may contain mistakes; the official description above is the record.