CVE-2026-74282 tipc: prevent snt_unacked underflow on CONN_ACK
A remote attacker can cause a denial of service in the Linux kernel TIPC protocol by sending a crafted connection acknowledgment that triggers an integer underflow.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74282?
CVE-2026-74282 is a high-severity vulnerability in Linux, published on 15 Aug 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:
tipc: prevent snt_unacked underflow on CONN_ACK
tipc_sk_conn_proto_rcv() subtracts the peer-supplied connection ack count from the unsigned 16-bit send counter snt_unacked without checking that it does not exceed the number of messages actually outstanding:
tsk->snt_unacked -= msg_conn_ack(hdr);
msg_conn_ack() is read straight from a received CONN_MANAGER/CONN_ACK message. If the ack count is larger than snt_unacked, the subtraction wraps to a near-maximum value, leaving tsk_conn_cong() permanently true and starving the connection of further transmits.
Validate the ACK count at the start of the CONN_ACK block and drop the message if it acknowledges more messages than are outstanding. A peer (or, for a local connection, the connected peer socket) can otherwise wedge a TIPC connection's send side by sending an oversized connection ack.
Which versions are affected by CVE-2026-74282?
How do I fix CVE-2026-74282?
Apply the vendor's patch.
Is CVE-2026-74282 being exploited?
There is no known exploitation of CVE-2026-74282 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74282, DEBIAN-CVE-2026-74282, GHSA-5xv7-x5qx-3wv4, UBUNTU-CVE-2026-74282.