CVE-2026-80983 net/smc: fix socket refcount leak in smc_switch_conns()
A socket reference count leak in the Linux kernel SMC module can cause memory exhaustion and prevent network namespace teardown, leading to denial of service.
- 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-2026-80983?
CVE-2026-80983 is a denial of service 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: fix socket refcount leak in smc_switch_conns()
smc_switch_conns() takes a reference on the SMC socket before dropping lgr->conns_lock, so the connection stays alive while the CDC slot is fetched:
sock_hold(&smc->sk); read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); if (rc) goto err_out;
The err_out label only drops the wr_tx link reference, so this early exit returns without the matching sock_put(). The second error exit is not affected, because sock_put() has already run by then.
A leaked sk_refcnt means the smc_sock is never destroyed. Its send and receive buffers stay allocated, and for a user socket the reference held on the network namespace is never released, so the netns can no longer be torn down.
smc_cdc_get_free_slot() fails when the target link goes down or when the connection has been killed while the switch is in progress. Both are reachable during the link failover this function implements, so the leak is triggered by the same hardware events that make smc_switch_conns() run in the first place.
Restructure so there is a single sock_put() covering both outcomes, instead of adding a second one to the error path.
Which versions are affected by CVE-2026-80983?
How do I fix CVE-2026-80983?
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-2026-80983 being exploited?
There is no known exploitation of CVE-2026-80983 in the wild and no public exploit code.
Sources
Also known as AZL-100289, BELL-CVE-2026-80983, DEBIAN-CVE-2026-80983, GHSA-6pmg-4m98-jhww, UBUNTU-CVE-2026-80983.