CVE-2026-80984 net/smc: do not dereference an unset send buffer on the SMC-D teardown path
A null pointer dereference in the Linux kernel SMC-D teardown path allows remote attackers to cause a denial of service via crafted network traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80984?
CVE-2026-80984 is a vulnerability in Linux, published on 11 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:
net/smc: do not dereference an unset send buffer on the SMC-D teardown path
smc_close_stream_wait() calls smc_tx_prepared_sends() from inside its sk_wait_event() condition, and sk_wait_event() evaluates that condition once with the socket lock released. smcd_buf_detach() clears conn->sndbuf_desc from smc_conn_kill() under lock_sock(), so a link group terminating while a socket waits there leaves the helper dereferencing NULL, faulting out of close(). SIOCOUTQ reads the field by hand, and smc_close_cancel_work() drops the lock across two cancel_*_sync() calls.
Sample the pointer once in the helper, report nothing prepared while it is unset, and bound the ioctl the same way. The receive tasklet dereferences the field directly in smc_cdc_msg_recv_action(), not through this helper; 1/2 is what keeps it from running that late.
Which versions are affected by CVE-2026-80984?
How do I fix CVE-2026-80984?
Apply the vendor's patch.
Is CVE-2026-80984 being exploited?
There is no known exploitation of CVE-2026-80984 in the wild and no public exploit code.
Sources
Also known as AZL-100223, BELL-CVE-2026-80984, DEBIAN-CVE-2026-80984, GHSA-r783-4vmj-f363, UBUNTU-CVE-2026-80984.