CVE-2026-63982 net/sched: Fix ethx:ingress -> ethy:egress -> ethx:ingress mirred loop
A local attacker with high privileges can cause a denial of service by creating a network packet mirroring loop that bypasses loop detection.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-63982?
CVE-2026-63982 is a denial of service vulnerability in Linux, published on 19 Jul 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:
net/sched: Fix ethx:ingress -> ethy:egress -> ethx:ingress mirred loop
When mirred redirects to ingress (from either ingress or egress) the loop state from sched_mirred_dev array dev is lost because of 1) the packet deferral into the backlog and 2) the fact the sched_mirred_dev array is cleared. In such cases, if there was a loop we won't discover it.
Here's a simple test to reproduce: ip a add dev port0 10.10.10.11/24
tc qdisc add dev port0 clsact tc filter add dev port0 egress protocol ip \ prio 10 matchall action mirred ingress redirect dev port1
tc qdisc add dev port1 clsact tc filter add dev port1 ingress protocol ip \ prio 10 matchall action mirred egress redirect dev port0
ping -c 1 -W0.01 10.10.10.10
Which versions are affected by CVE-2026-63982?
How do I fix CVE-2026-63982?
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-2026-63982 being exploited?
There is no known exploitation of CVE-2026-63982 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-63982, GHSA-g6rc-cvjj-cfmj, UBUNTU-CVE-2026-63982.