# CVE-2026-98035: bpf: Cancel special fields when recycling rhtab elements

> A race condition in Linux kernel BPF hash map recycling allows unsafe field release in NMI context, potentially leading to privilege escalation or denial of service.

- **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:** DEBIAN-CVE-2026-98035, GHSA-xmmm-c56c-hjqv, UBUNTU-CVE-2026-98035

## What is CVE-2026-98035?

CVE-2026-98035 is a 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: Cancel special fields when recycling rhtab elements

rhtab_map_update_existing() and rhtab_delete_elem() call
bpf_obj_free_fields() when replacing or deleting a value. These map
operations can run from BPF programs in NMI context, where releasing a
referenced kptr or another complex field is not generally safe.

Array and hash maps avoid that problem by cancelling only the asynchronous
fields which can be stopped safely in the caller context. Other ownership
state remains attached to the allocation until its memory allocator
destructor performs the final cleanup.

Use bpf_obj_cancel_fields() for the corresponding rhtab paths as well. This
cancels timers, workqueues, and task work while allowing rhtab_mem_dtor() to
release referenced kptrs when the allocation is eventually destroyed.

[ kkd: Rebased, used direct helper calls, and rewrote the commit log ]

## Which versions are affected by CVE-2026-98035?


## How do I fix CVE-2026-98035?

Apply the vendor's patch.

## Is CVE-2026-98035 being exploited?

There is no known exploitation of CVE-2026-98035 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98035 and fix it if it is affected.

What it is: CVE-2026-98035 is a 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-2026-98035 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-2026-98035/ (Markdown: https://insights.sbomify.com/CVE-2026-98035/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98035
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98035
- OSV: https://osv.dev/vulnerability/CVE-2026-98035

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98035/
Summaries are generated and may contain mistakes; the official description above is the record.