CVE-2026-80979 net/smc: unregister the connection before draining the rx tasklet
A use-after-free in the Linux kernel SMC subsystem allows attackers to cause denial of service or execute code via race conditions during connection teardown.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80979?
CVE-2026-80979 is a high-severity use after free vulnerability in Linux, published on 11 Sep 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/smc: unregister the connection before draining the rx tasklet
smc_conn_free() calls smc_ism_unset_conn() only while the link group is still on its device list, and never sets conn->killed. smc_lgr_terminate_sched() unlinks the group immediately and defers killing its connections to a work item, so a connection freed in that window keeps its smcd->conn[] slot with both gates in smcd_handle_irq() open, and the device can re-arm the receive tasklet after tasklet_kill() has returned. On the DMB-nocopy path the ghost send buffer is freed right after that drain, so the re-armed tasklet dereferences it.
Unregister unconditionally and drain before the detach at both teardown sites, mirroring rmb_desc, which smc_buf_unuse() releases after the drain. Clear conn->sndbuf_desc before freeing it as well, so a reader that samples the pointer cannot get one that is already freed.
Which versions are affected by CVE-2026-80979?
How do I fix CVE-2026-80979?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-80979 being exploited?
There is no known exploitation of CVE-2026-80979 in the wild and no public exploit code.
Sources
Also known as AZL-100082, BELL-CVE-2026-80979, DEBIAN-CVE-2026-80979, GHSA-3r27-v3q5-phcc, UBUNTU-CVE-2026-80979.