CVE-2026-98422 wifi: mac80211: reset the AP_VLAN tailroom counter on ifdown
A logic error in the Linux kernel Wi-Fi subsystem allows a local attacker to trigger a kernel warning and potential denial of service by repeatedly toggling AP VLAN interfaces.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98422?
CVE-2026-98422 is a denial of service vulnerability in Linux, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: reset the AP_VLAN tailroom counter on ifdown
On ifup, AP_VLAN interfaces get crypto_tx_tailroom_needed_cnt from the AP interface, but it's never decremented again unless the AP is also brought down. Thus, bringing the same AP_VLAN up again will increment the counter again and eventually hit the sanity check:
WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt != master->crypto_tx_tailroom_needed_cnt);
Reset it on ifdown to avoid that.
Which versions are affected by CVE-2026-98422?
How do I fix CVE-2026-98422?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-98422 being exploited?
There is no known exploitation of CVE-2026-98422 in the wild and no public exploit code.
Sources
Also known as AZL-108110, BELL-CVE-2026-98422, DEBIAN-CVE-2026-98422, GHSA-7fq6-p34m-gv65, UBUNTU-CVE-2026-98422.