CVE-2026-80846 xfrm: drop ESP-in-TCP packets with no ingress device
A null pointer dereference in the Linux kernel's XFRM subsystem allows remote attackers to cause a denial of service via crafted ESP-in-TCP packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80846?
CVE-2026-80846 is a vulnerability in Linux, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xfrm: drop ESP-in-TCP packets with no ingress device
ESP-in-TCP receives records through the TCP strparser. handle_esp() restores skb->dev from the saved skb_iif before passing the packet into the XFRM input path.
Queued TCP data can be processed after the original ingress device has been removed, for example during veth or net namespace teardown. In that case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input paths both expect skb->dev to be valid while building the route lookup, so queued ESP-in-TCP data can dereference a NULL device.
Drop the packet if the saved ingress device can no longer be resolved. Such a packet can no longer be routed through the normal XFRM receive path, and this preserves the existing behaviour for packets whose ingress device still exists.
Which versions are affected by CVE-2026-80846?
How do I fix CVE-2026-80846?
Apply the vendor's patch.
Is CVE-2026-80846 being exploited?
There is no known exploitation of CVE-2026-80846 in the wild and no public exploit code.
Sources
Also known as AZL-99431, BELL-CVE-2026-80846, DEBIAN-CVE-2026-80846, GHSA-7qhp-m2hr-xxjv, UBUNTU-CVE-2026-80846.