---
id: "CVE-2026-98810"
kind: "vulnerability"
aliases: ["CVE-2026-98810"]
title: "Linux kernel: mac80211 monitor mode reads past packet buffer"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "mac80211", "runtime", "wifi"]
not_affected_if: ["no-monitor-mode", "no-wifi-hardware"]
published_at: "2026-10-18T16:17:35+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:14:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98810", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: mac80211 monitor mode reads past packet buffer

A bounds check in the Linux kernel's mac80211 Wi-Fi monitor-mode code uses the total packet length instead of the linear buffer length, so a large AF_PACKET frame can cause an out-of-bounds read. The sources do not state what an attacker gains beyond a kernel memory read.

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

## How to check

- Run `uname -r` and compare against the fixed kernel release in your distribution's advisory: unknown
- Check whether the mac80211 module is loaded with `lsmod | grep mac80211`; unknown if the sources do not say more

## Fix

- Update the Linux kernel to a release that includes the upstream fix for ieee80211_monitor_select_queue(): unknown exact version
- Reboot after installing the kernel update

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98810

## From the sources

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

wifi: mac80211: fix slab-out-of-bounds read in ieee80211_monitor_select_queue()

ieee80211_monitor_select_queue() validates the skb length using skb->len
before dereferencing pointers into skb->data to access the 802.11 header.
However, skb->len includes data in both the linear head buffer and
non-linear fragments/pages. When AF_PACKET sends a packet large enough to
become non-linear, the 802.11 header at skb->data + len_rthdr may extend
past the linear head buffer even though skb->len appears sufficient.

This leads to a slab-out-of-bounds read when accessing hdr->frame_control,
as the kernel reads beyond the allocated skb head buffer:

  BUG: KASAN: slab-out-of-bounds in ieee80211_monitor_select_queue+0x1ed/0x220

syzbot has hit the same issues.

Fix this by checking skb_headlen(skb) (which gives the length of the
linear data region) instead of skb->len before dereferencing skb->data
pointers. This ensures the required bytes are actually present in the
linear portion of the skb.

Apply the same fix to ieee80211_validate_radiotap_len() which has the
same class of bug: it uses skb->len to validate accesses to skb->data,
and to the corresponding checks in ieee80211_monitor_start_xmit(): for
drivers advertising NETIF_F_SG the skb is not linearized before
ndo_start_xmit, so the 802.11 header can be read past the linear
buffer there as well.

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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_