CVE-2026-90226 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel security, particularly those handling NFC LLCP operations, should assess exposure and prioritize patching affected versions. Linux kernel security defenders should review and update NFC LLCP handling to reject invalid optlen values. Security teams handling NFC LLCP operations should monitor Linux kernel updates and apply patches promptly to prevent potential buffer overflows and data corruption.

Why it matters

Defenders should prioritize patching Linux kernel versions affected by this vulnerability, particularly those handling NFC LLCP operations, to prevent potential buffer overflows and data corruption.

• Potential buffer overflow and data corruption
• Violation of getsockopt(2) contract
• Necessity to verify and apply patches
• Potential for denial-of-service or privilege escalation

Technical summary

The Linux kernel's NFC LLCP implementation has a vulnerability that can cause a userspace overflow when handling invalid optlen values. The nfc_llcp_getsockopt() function casts optval to (u32 __user *) and stores 4 bytes regardless of the caller-supplied optlen, leading to potential buffer overflows. This issue arises from the nfc_llcp_getsockopt() function, which does not properly 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'

Defensive priority

Defenders should prioritize verifying and applying patches for Linux kernel versions affected by this vulnerability, particularly those handling NFC LLCP operations.

Recommended defensive actions

• Verify and apply patches for Linux kernel versions affected by this vulnerability
• Review and update NFC LLCP handling to reject invalid optlen values
• Monitor Linux kernel updates and apply patches promptly
• Review compensating controls for exposed systems while remediation is scheduled and verified
• 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

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description and affected versions. However, specific exploitation details or victim information are not provided. Linux kernel versions affected by this vulnerability require verification and patching to prevent potential buffer overflows and data corruption. Defenders should verify and apply patches for Linux kernel versions affected by this vulnerability, particularly those handling NFC LLCP operations. The nfc_llcp_getsockopt() function casts optval

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.