# CVE-2026-98589: bpf: Reject pkt arguments in mutating subprogs

> A Linux kernel BPF verifier flaw allows memory corruption via packet pointers in mutating subprograms, enabling local privilege escalation.

- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109116, BELL-CVE-2026-98589, DEBIAN-CVE-2026-98589, GHSA-2cxv-r576-wfcv, UBUNTU-CVE-2026-98589

## What is CVE-2026-98589?

CVE-2026-98589 is a memory corruption vulnerability in Linux, published on 18 Oct 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 pkt arguments in mutating subprogs

The verifier tracks changes in how PTR_TO_PACKET registers'
bounds are modified across subprog boundaries. PTR_TO_PACKET
registers are actually passed as PTR_TO_MEM, which is assumed
valid for the entire call. This is not the case with packet memory,
where a pskb_* call may invalidate its memory region.

Reject BPF code that passes PTR_TO_PACKET pointers to subprogs that
may mutate a packet. We cannot pass the pointer as a true PTR_TO_PACKET
because we would also need to somehow pass the PTR_TO_PACKET_META
or PTR_TO_PACKET_END to the subprog. Since we cannot avoid representing
the pointer in the subprog as PTR_TO_MEM, only permit it if the
subprog is guaranteed not to mutate the packet.

## Which versions are affected by CVE-2026-98589?


## How do I fix CVE-2026-98589?

Apply the vendor's patch.

## Is CVE-2026-98589 being exploited?

There is no known exploitation of CVE-2026-98589 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98589 and fix it if it is affected.

What it is: CVE-2026-98589 is a memory corruption vulnerability in Linux, published on 18 Oct 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-2026-98589 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-2026-98589/ (Markdown: https://insights.sbomify.com/CVE-2026-98589/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98589
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98589
- OSV: https://osv.dev/vulnerability/CVE-2026-98589

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98589/
Summaries are generated and may contain mistakes; the official description above is the record.