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CVE-2026-89524
wifi: ath6kl: clamp assoc request/response lengths before subtracting IE offsets
Published 2026-09-11 (37 days 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-2026-89524 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-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ath6kl_cfg80211_connect_event() subtracts fixed IE offsets from assoc_req_len (-= 4) and assoc_resp_len (-= 6), both u8, with no lower bound. The aggregate check recently added to ath6kl_wmi_connect_event_rx() bounds the declared lengths from above (their sum must fit the received event), but an assoc request/response shorter than its fixed offset still underflows here: the u8 wraps to ~250, and cfg80211_connect_result() / cfg80211_roamed() then treat that wrapped value as the IE length and copy that many bytes out of the small assoc_info buffer to user space via nl80211, disclosing adjacent slab memory. Clamp both lengths to their offsets before subtracting. Found by 0sec (https://0sec.ai) using automated source analysis; the missing lower bound is evident from source. Compile-tested.
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/cfg80211.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
- 2026-09-11 (37 days ago)source
- CVSS
- 8.1 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.27%, higher than 18.5% 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 | 5.10.270 | 225587bdbf4b |
| 3.2 | 5.15.221 | d337213a8897 |
| 3.2 | 6.1.188 | e11d5ae96d5e |
| 3.2 | 6.6.157 | 6deb4d7a0c3d |
| 3.2 | 6.12.109 | e3619bed5da1 |
| 3.2 | 6.18.50 | e1330d719c04 |
| 3.2 | 7.2.4 | 8eb73016fb39 |
| 3.2 | 7.3 | 3bbd05723d15 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | 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 fullMAC WiFi driver; assoc_req_len/assoc_resp_len come from a WMI_CONNECT_EVENT built from the 802.11 association exchange. A rogue or evil-twin AP, or a frame injector in radio range, supplies a truncated assoc/reassoc response, so the attacker must share the wireless segment.
- AC:LAttack complexity, low
- A malicious AP can send a truncated association or reassociation response so firmware reports assoc_req_len < 4 or assoc_resp_len < 6. The u8 subtraction wraps deterministically and cfg80211 copies the wrapped length; the attacker can force (re)association or roaming with deauth until the event is emitted.
- PR:NPrivileges required, none
- The WMI connect event is handled on the firmware receive path with no capability check, local account, or user-namespace gate. An adjacent attacker needs no privileges on the victim system.
- UI:NUser interaction, none
- Devices with a saved or open profile auto-associate, and the SME_CONNECTED roam path (cfg80211_roamed) delivers the same underflowed IEs while already connected, so no extra victim action is required.
- S:UScope, unchanged
- The out-of-bounds read, kernel-memory disclosure, and any resulting oops stay inside the host kernel's security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- After the u8 wrap, cfg80211_connect_result()/cfg80211_roamed() treat ~250-byte lengths as IE sizes and copy that many bytes from the small assoc_info skb into nl80211 CONNECT/ROAM events (and WEXT assoc IE events), disclosing adjacent slab memory far beyond a few bytes.
- I:NIntegrity impact, none
- The underflow only inflates the length used for an out-of-bounds read and copy to userspace; no kernel memory is written out of bounds and no attacker-controlled pointer is used to modify kernel state.
- A:HAvailability impact, high
- Copying ~250 bytes past a short WMI skb can walk off the slab object into unmapped or redzoned memory, causing a kernel oops or KASAN panic that an adjacent attacker can retrigger by repeating association.