CVE-2026-80800 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel and NFC implementation security should assess exposure and prioritize patching. This includes operators, security teams, and vulnerability management teams that need to verify patch application, review NFC implementation for potential exposure, and monitor for potential exploitation attempts.

Why it matters

CVE-2026-80800 is a vulnerability in the Linux kernel's NFC LLCP implementation that allows for an unbounded TLV walk. Defenders should prioritize verifying and applying patches, reviewing NFC implementation for potential exposure, and monitoring for potential exploitation attempts.

• Potential for out-of-bounds reads and denial of service
• Requires verification of patch application and NFC implementation security
• May allow for exploitation by nearby NFC devices without authentication

Technical summary

The nfc_llcp_connect_sn() function in the Linux kernel's NFC LLCP implementation did not properly bound the TLV list walk, allowing for potential out-of-bounds reads. This has been resolved through patches that bound the walk and validate lengths. The issue allows for an unbounded TLV walk in the nfc_llcp_connect_sn() function, which can be triggered by a nearby NFC device without authentication, as LLCP link activation occurs automatically after NFC-DEP. The commits that fixed the issue are 27256cdb290e and d8bd2dedbde5.

Defensive priority

Defenders should prioritize verifying and applying patches for this vulnerability, particularly for systems using NFC functionality.

Recommended defensive actions

• Verify and apply patches for this vulnerability
• Review NFC implementation for potential exposure
• Monitor for potential exploitation attempts
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The vulnerability was found by 0sec automated security-research tooling and resolved through commits that bound the TLV walk and validated lengths. The issue is reachable from nfc_llcp_recv_connect() and nfc_llcp_recv_cc(), i.e., from received CONNECT and CC PDUs. A nearby NFC device can reach this without authentication; LLCP link activation happens automatically after NFC-DEP. Defenders should verify patch application, review NFC implementation for potential exposure, and monitor for potential exploitation attempts. The commits that

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.