Medium [CVE-2026-74282] prevent snt_unacked underflow on CONN_ACK
This medium-severity Red Hat Linux advisory covers CVE-2026-74282 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
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. A flaw was found in the Linux kernel's Transparent Inter-Process Communication (TIPC) component.
A remote or local attacker could send an oversized connection acknowledgment (ACK) message, leading to an integer underflow. This underflow can cause the connection to become permanently congested, effectively starving it of further transmissions and resulting in a Denial of Service (DoS).
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
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