# CVE-2026-80798: nfc: llcp: reject PDUs shorter than the LLCP header

> An attacker with nearby NFC access can trigger an out-of-bounds read in the Linux kernel LLCP handler, potentially causing a crash or leaking memory.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99681, BELL-CVE-2026-80798, DEBIAN-CVE-2026-80798, GHSA-p65w-76hh-qj57, UBUNTU-CVE-2026-80798

## What is CVE-2026-80798?

CVE-2026-80798 is a vulnerability in Linux, published on 4 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: reject PDUs shorter than the LLCP header

Every LLCP PDU begins with a two-byte header (DSAP/SSAP + PTYPE), but the
receive path never checked that a frame is at least LLCP_HEADER_SIZE bytes
before parsing it.

nfc_llcp_rx_skb() reads the header via nfc_llcp_ptype()/nfc_llcp_dsap()/
nfc_llcp_ssap(), which dereference pdu->data[0] and pdu->data[1], and a
CONNECT or CC PDU then computes

	tlv_array_len = skb->len - LLCP_HEADER_SIZE;

as a size_t and hands it to the TLV walk. When the frame is shorter than
the header the subtraction wraps to a huge value and the walk runs far
past the buffer, an out-of-bounds read.

A nearby NFC device can reach this without authentication; LLCP link
activation happens automatically after NFC-DEP.

Guard the common receive choke point __nfc_llcp_recv(), shared by both the
target (nfc_llcp_data_received()) and initiator (nfc_llcp_recv()) paths, so
a short skb is dropped before the rx_work worker parses it. Use
pskb_may_pull() rather than a skb->len test so the two header bytes are
guaranteed to sit in the skb linear area even for a non-linear skb,
matching how the sibling NCI and HCI receive paths validate their headers.

Reproduced with a KFENCE out-of-bounds read via /dev/virtual_nci on
linux-next.

Found by 0sec automated security-research tooling (https://0sec.ai).

## Which versions are affected by CVE-2026-80798?


## How do I fix CVE-2026-80798?

Apply the vendor's patch.

## Is CVE-2026-80798 being exploited?

There is no known exploitation of CVE-2026-80798 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80798 and fix it if it is affected.

What it is: CVE-2026-80798 is a vulnerability in Linux, published on 4 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-2026-80798 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-2026-80798/ (Markdown: https://insights.sbomify.com/CVE-2026-80798/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80798
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80798
- OSV: https://osv.dev/vulnerability/CVE-2026-80798

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80798/
Summaries are generated and may contain mistakes; the official description above is the record.