CVE-2026-80980 net/smc: stop killed, freed and out_of_sync sharing a byte
A race condition in Linux kernel SMC networking allows concurrent flag updates to corrupt connection state, potentially causing data corruption or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80980?
CVE-2026-80980 is a critical 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: stop killed, freed and out_of_sync sharing a byte
The three connection state flags are single-bit bitfields, so they occupy one byte of struct smc_connection and every store to one is a read-modify-write of the other two:
u8 killed : 1; u8 freed : 1; u8 out_of_sync : 1;
They are not written under a common lock. smc_cdc_msg_validate() sets out_of_sync from the receive tasklet, while smc_conn_kill() sets killed from process context under lock_sock(), and the receive path does not defer to the backlog when the socket is owned -- smc_cdc_msg_recv() takes only bh_lock_sock().
Give each flag its own byte so a store no longer touches its neighbours. All readers test them as booleans and are unchanged. struct smc_connection grows by two bytes.
Which versions are affected by CVE-2026-80980?
How do I fix CVE-2026-80980?
Apply the vendor's patch.
Is CVE-2026-80980 being exploited?
There is no known exploitation of CVE-2026-80980 in the wild and no public exploit code.
Sources
Also known as AZL-100361, BELL-CVE-2026-80980, DEBIAN-CVE-2026-80980, GHSA-74wv-6pxv-7x55, UBUNTU-CVE-2026-80980.