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CVE-2026-98339
wifi: cfg80211: don't filter by BSS type when removing stale entries
Published 2026-10-06 (13 days ago) by the Linux kernel CNA. Subsystem net/wireless. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-98339 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-6568-1 · 2026-10-16 · text | 6.12.113-1 | Update the kernel and reboot. DSA-6568-1 shipped the fix on 2026-10-16, in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.8-1 | Update the kernel and reboot. Fixed in 7.2.8-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When an assoc AP switches to a channel that already has a BSS entry, cfg80211_update_assoc_bss_entry() removes that entry before rehashing the real one, since the two would otherwise collide in the BSS rbtree. The lookup for that entry also required it to match the connection's BSS type, so an entry advertising e.g. the IBSS capability bit was left in place, and the following cfg80211_rehash_bss() then ran into it: WARN_ON(!cmp) Changing the type shouldn't really happen, but can be triggered by a rogue AP/device, so drop the check and remove any entries matching the comparison.
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.
net/wireless/scan.c
- What this is
- 802.11 (including CFG80211/NL80211)MAINTAINERS section matched on net/wireless/ · linux-wireless@vger.kernel.org · Maintained
- Kernel module
- cfg80211
Check it on the machine
grep -wE 'CONFIG_CFG80211|CONFIG_WIRELESS' /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 cfg80211Prints 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
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_CFG80211, CONFIG_WIRELESS
- 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
- 2026-10-06 (13 days 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
- 0.29%, higher than 19.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/wireless
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.4 | 5.10.271 | 6ef87a853327 |
| 5.4 | 5.15.222 | 1380ee3a202d |
| 5.4 | 6.1.189 | fb445ec7480d |
| 5.4 | 6.6.158 | 65fdb973bd90 |
| 5.4 | 6.12.112 | 64e23a36d8f0 |
| 5.4 | 6.18.54 | 6d2fd2618567 |
| 5.4 | 7.2.8 | 0aa44982125c |
| 5.4 | 7.3 | b377e1000d96 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DSA-6568-1 | 2026-10-16 | trixie 6.12.113-1 | 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
- The bad state comes from received 802.11 frames: a beacon/probe response carrying the associated AP's BSSID+SSID with the IBSS capability bit on another channel, then a CSA beacon that leads to cfg80211_ch_switch_notify() -> cfg80211_update_assoc_bss_entry(). The attacker must be in WiFi radio range.
- AC:LAttack complexity, low
- The attacker produces every step: injecting the colliding scan entry, sending the CSA (beacons are unprotected without beacon protection), then a second CSA or going silent so connection loss calls cfg80211_unlink_bss(). cmp_bss() ignores capability, so the rb_insert_bss() collision always happens.
- PR:NPrivileges required, none
- No credentials are needed. A rogue AP, or an attacker spoofing management beacons of the victim's AP, triggers mac80211 channel-switch processing and scan-entry creation before any authenticated data exchange.
- UI:NUser interaction, none
- The victim station only needs to be in its normal associated state. Beacon/CSA processing and the later beacon-loss unlink happen automatically, with no user action.
- S:UScope, unchanged
- The corruption is confined to cfg80211's BSS list and rbtree within the same kernel. There is no hypervisor or other security-authority boundary crossed.
- C:HConfidentiality impact, high
- After the failed rehash the connected BSS has stale rbn pointers. A second CSA makes cfg80211_rehash_bss() rb_erase() that non-member node, rewriting live parent/child links so bss_tree can reference entries later freed on expiry. That is a use-after-free on every rb lookup triggered by a received beacon.
- I:HIntegrity impact, high
- The double rb_erase() of the stale cbss->rbn and the list_del() leaving poisoned pointers on a still-referenced BSS corrupt kernel heap metadata (tree links, bss_entries). The resulting use-after-free of cfg80211_internal_bss objects is a write-capable memory-corruption primitive.
- A:HAvailability impact, high
- After cfg80211_rehash_bss() list_del()s the connected BSS, beacon-loss handling calls cfg80211_unlink_bss() -> __cfg80211_unlink_bss() -> list_del_init() on LIST_POISON pointers and faults (oops/panic). WARN_ON(!cmp) also panics with panic_on_warn.