---
id: "CVE-2026-98698"
kind: "vulnerability"
aliases: ["CVE-2026-98698"]
title: "Linux kernel: empty FILS association request can crash Wi-Fi stack"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "kernel", "linux", "mac80211", "self-hosted", "wifi"]
not_affected_if: ["no-mac80211", "no-wifi"]
published_at: "2026-10-18T16:17:23+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:18:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98698", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: empty FILS association request can crash Wi-Fi stack

A crafted (Re)Association Request with an empty FILS payload makes the mac80211 Wi-Fi code pass an invalid pointer to the crypto layer. The sources describe a kernel BUG with CONFIG_DEBUG_SG and mishandled memory without it, so the likely outcome is a crash or memory corruption.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- `uname -r` and compare against the fixed kernel builds in the NVD entry for CVE-2026-98698
- `grep -i fils /proc/config.gz` or check the kernel config for `CONFIG_DEBUG_SG` (unknown whether the sources name a specific config gate)

## Fix

- Update the Linux kernel to a release that includes the mac80211 FILS fix (fixed version unknown from the sources)
- Until patched, unknown whether disabling FILS or a driver-side mitigation applies

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98698

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: handle empty FILS association request payload

fils_encrypt_assoc_req() accepts a (Re)Association Request frame whose
last element is the FILS Session element.  crypt_len is then zero and
aes_siv_encrypt() is called with an empty plaintext.

kmemdup() returns ZERO_SIZE_PTR for a zero-length allocation, so the
unconditional sg_init_one() puts an invalid page into the scatterlist.
With CONFIG_DEBUG_SG this triggers a kernel BUG in sg_set_buf();
without the debug check the bogus page is handed to the crypto backend.

AES-SIV is defined for empty plaintext and the S2V result is then the
complete output, so handle this case before the CTR step, which has
nothing to encrypt.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_