---
id: "CVE-2026-98707"
kind: "vulnerability"
aliases: ["CVE-2026-98707"]
title: "Linux kernel: Wi-Fi block-ack timer can fire after session teardown"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "linux-kernel", "mac80211", "wifi"]
not_affected_if: ["no-wifi-hardware"]
published_at: "2026-10-18T16:17:24+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:18:49+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98707", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel: Wi-Fi block-ack timer can fire after session teardown

In the Linux kernel's mac80211 Wi-Fi stack, the receive block-ack session timer can stay queued after the session's memory is freed, and a stale handler can rearm it. The sources do not say what an attacker gets beyond a use-after-free in kernel memory, which typically means a crash or possible code execution.

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

## How to check

- Check the running kernel version with `uname -r` and compare it against the fixed kernel release in the upstream kernel git history for CVE-2026-98707.
- Check whether the mac80211 Wi-Fi stack is in use with `lsmod | grep mac80211`.
- unknown

## Fix

- Update the Linux kernel to a release that includes the upstream commit titled 'wifi: mac80211: shut down RX BA session timer on teardown'; the sources do not give a version number.
- unknown

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98707

## From the sources

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

wifi: mac80211: shut down RX BA session timer on teardown

Tearing down an RX BA session can leave the session timer queued on a
freed tid_rx. Later timer-wheel processing and the timer callback itself
then run against freed memory.

An RX BAR handler can dereference tid_rx under RCU before teardown
unpublishes it and stay in its read-side critical section while teardown
deletes the session timer. The stale handler can then rearm the timer
after timer_delete_sync() returns and before the RCU callback frees
tid_rx.

Use timer_shutdown_sync() so rearm attempts become ineffective once
teardown starts. Keep reorder_timer unchanged: teardown marks the session
removed under reorder_lock and its release path checks that state before
rearming. session_timer has no equivalent guard because
ieee80211_rx_h_ctrl() rearms it before taking reorder_lock.

---

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