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CVE-2026-68198
wifi: ath6kl: fix use-after-free in aggr_reset_state()
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68198 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The aggr_reset_state() function uses timer_delete() (non-synchronous) for the aggregation timer before proceeding to delete TID state and before the structure is freed by callers like aggr_module_destroy(). If the timer callback (aggr_timeout) is executing when aggr_reset_state() is called, the callback will continue to access aggr_conn fields like rx_tid[] and stat[] which may be freed immediately after by kfree(aggr_info->aggr_conn) in aggr_module_destroy(). Additionally, the timer callback can re-arm itself via mod_timer() while aggr_reset_state() is running, creating a more complex race condition. Use timer_delete_sync() instead to ensure any running timer callback has completed before returning.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/wireless/ath/ath6kl/txrx.c
- What this is
- ATHEROS ATH6KL WIRELESS DRIVERMAINTAINERS section matched on drivers/net/wireless/ath/ath6kl/ · linux-wireless@vger.kernel.org · Orphan
- Kernel module
- ath6kl_core
Check it on the machine
grep -wE 'CONFIG_ATH6KL|CONFIG_WLAN|CONFIG_WLAN_VENDOR_ATH' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ath6kl_corePrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_ATH6KL, CONFIG_WLAN, CONFIG_WLAN_VENDOR_ATH
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-10 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.27%, higher than 18.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.2 | 5.10.266 | a1bac650b2d6 |
| 3.2 | 5.15.217 | 2132a6db0584 |
| 3.2 | 6.1.184 | 17ff29cd8dbc |
| 3.2 | 6.6.151 | 64af6534a085 |
| 3.2 | 6.12.103 | b5d618fd61b9 |
| 3.2 | 6.18.42 | 18965470d41e |
| 3.2 | 7.1.6 | a3313111b5d9 |
| 3.2 | 7.2 | ba7debb4dd64 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- ath6kl is a WiFi driver; the race is driven by 802.11 frames from an adjacent attacker — a gapped A-MPDU sequence arms the reorder timer and a deauth/disassoc or connect/disconnect event drives aggr_reset_state() via ath6kl_disconnect_event()/ath6kl_connect_event()/ath6kl_sta_cleanup(). This requires radio proximity, not routable network access.
- AC:LAttack complexity, low
- The attacker controls both sides of the race: transmitting out-of-order aggregated frames arms aggr_conn->timer, and a deauth/disassoc or reconnect immediately invokes aggr_reset_state(), which frees rx_tid[].hold_q and (via aggr_module_destroy) aggr_conn itself while aggr_timeout() may be running or re-arming via mod_timer(). The sequence can be repeated indefinitely until the window is hit.
- PR:NPrivileges required, none
- No privileges or account on the target system are required; a rogue AP the client associates with, or an attacker injecting unprotected deauth/disassoc frames at a station with an active block-ack session, is sufficient. In AP mode, a station joining an open network can trigger the same path on disconnect.
- UI:NUser interaction, none
- The station already associated and receiving aggregated traffic is enough; deauth/disassoc handling and the resulting aggr_reset_state() run automatically in the driver with no action by the device owner.
- S:UScope, unchanged
- The use-after-free is on kernel heap memory owned by the ath6kl driver and stays within the kernel's own security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- The freed aggr_info_conn and hold_q allocations can be reclaimed and refilled with attacker-influenced data (e.g. sk_buff payloads from injected frames), so the concurrent callback reading rx_tid[]/stat[]/hold_q[] yields a controllable read primitive that can leak kernel memory contents.
- I:HIntegrity impact, high
- aggr_timeout() writes through the freed object — setting timer_scheduled, rxtid->timer_mon, dequeuing skbs from hold_q[] and calling mod_timer() on a freed timer_list — giving arbitrary writes into reclaimed heap objects and list corruption that is a classic path to control-flow hijack.
- A:HAvailability impact, high
- Even without successful heap grooming, the use-after-free and the double-free/dangling-skb access in aggr_deque_frms() reliably produce slab corruption and a kernel oops or panic, and the attacker can repeat the trigger at will.