# CVE-2026-98611: bpf: Check params size before reading reserved fields

> A local attacker with BPF privileges can read kernel memory beyond validated bounds due to missing size checks in bpf_crypto_ctx_create.

- **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:** BELL-CVE-2026-98611, DEBIAN-CVE-2026-98611, GHSA-3j3q-mxmx-xwq4, UBUNTU-CVE-2026-98611

## What is CVE-2026-98611?

CVE-2026-98611 is a 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: Check params size before reading reserved fields

bpf_crypto_ctx_create() is a kfunc whose second argument is declared
with the __sz annotation, so the verifier only guarantees that
params__sz bytes of params are valid.  The function nevertheless reads
params->reserved[0] and params->reserved[1] (offsets 14 and 15) before
comparing params__sz against the size of struct bpf_crypto_params, so a
BPF program can pass a shorter buffer and have the kernel read past the
region that was validated for it.

Move the size check in front of the reserved field reads.

## Which versions are affected by CVE-2026-98611?


## How do I fix CVE-2026-98611?

Apply the vendor's patch.

## Is CVE-2026-98611 being exploited?

There is no known exploitation of CVE-2026-98611 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98611 and fix it if it is affected.

What it is: CVE-2026-98611 is a 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-2026-98611 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-2026-98611/ (Markdown: https://insights.sbomify.com/CVE-2026-98611/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98611
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98611
- OSV: https://osv.dev/vulnerability/CVE-2026-98611

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98611/
Summaries are generated and may contain mistakes; the official description above is the record.