# CVE-2026-90226: nfc: llcp: avoid userspace overflow on invalid optlen

> A local attacker can trigger a buffer overflow in the Linux kernel NFC LLCP module via getsockopt, potentially leading to privilege escalation or code execution.

- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102093, BELL-CVE-2026-90226, DEBIAN-CVE-2026-90226, GHSA-phjm-5cmf-7w3f, UBUNTU-CVE-2026-90226

## What is CVE-2026-90226?

CVE-2026-90226 is a memory corruption 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:

nfc: llcp: avoid userspace overflow on invalid optlen

nfc_llcp_getsockopt() casts optval to (u32 __user *) for put_user(), so
the kernel always stores 4 bytes regardless of the caller-supplied
optlen. The existing min_t(u32, len, sizeof(u32)) only clamps the length
reported back to userspace; it does not constrain the store. A call with
optlen < 4 therefore writes past the user buffer, violating the
getsockopt(2) contract for all five supported optnames.

Reject any call with optlen < sizeof(u32) up front. 'len' is int, so a
plain size comparison would promote a negative optlen to size_t and slip
past the check; an explicit 'len < 0' test is added first to catch
negative values before the size compare.

## Which versions are affected by CVE-2026-90226?


## How do I fix CVE-2026-90226?

Apply the vendor's patch.

## Is CVE-2026-90226 being exploited?

There is no known exploitation of CVE-2026-90226 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90226 and fix it if it is affected.

What it is: CVE-2026-90226 is a memory corruption 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-2026-90226 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-2026-90226/ (Markdown: https://insights.sbomify.com/CVE-2026-90226/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90226
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90226
- OSV: https://osv.dev/vulnerability/CVE-2026-90226

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90226/
Summaries are generated and may contain mistakes; the official description above is the record.