Description
In the Linux kernel, the following vulnerability has been resolved:
tcp: challenge ACK for non-exact RST in SYN-RECEIVED
The SYN-RECEIVED request-socket path in tcp_check_req() accepts an in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A non-exact RST therefore removes the request instead of eliciting a challenge ACK.
RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in SYN-RECEIVED: an exact RST resets the connection, while a non-exact in-window RST must trigger a challenge ACK and be dropped.
Apply that check before the ACK-field validation, following the RFC sequence-number, RST, then ACK processing order. Factor the per-netns challenge ACK quota out of tcp_send_challenge_ack() so request sockets can share it. Use the request socket's send_ack() callback and its own out-of-window ACK timestamp to send and rate-limit the response.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:HWeakness enumeration
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | >= 282f23c6ee343126156dd41218b22ece96d747e3, < c5dc463cc60eb26079b19607c9dbda76491dad05; >= 282f23c6ee343126156dd41218b22ece96d747e3, < 8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49; >= 282f23c6ee343126156dd41218b22ece96d747e3, < 0fe4636665d14a258de70b4f3e8248e6d42038f1; >= 282f23c6ee343126156dd41218b22ece96d747e3, < 234f9ffbd9b2c1b24ec67200ea3cff07401bec48; >= 282f23c6ee343126156dd41218b22ece96d747e3, < 22cec809b048495310f206d9abbcdbbfbdce3ae3; >= 282f23c6ee343126156dd41218b22ece96d747e3, < a28c4fcbf774e23b4779cae468e3497a5ad1f4a1; 86791bbfe5ed7b275be040cfeff049a1624af1b7; 61f69dc4e40e41b0018f00fa4aeb23d3239556fb; 34fb350281ced2a72707a5c0064f69992d440edb; >= 3.0.58, < 3.1; >= 3.2.37, < 3.3; >= 3.4.25, < 3.5 |
| Linux | Linux | 3.6 |
References
- https://git.kernel.org/stable/c/0fe4636665d14a258de70b4f3e8248e6d42038f1
- https://git.kernel.org/stable/c/22cec809b048495310f206d9abbcdbbfbdce3ae3
- https://git.kernel.org/stable/c/234f9ffbd9b2c1b24ec67200ea3cff07401bec48
- https://git.kernel.org/stable/c/8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49
- https://git.kernel.org/stable/c/a28c4fcbf774e23b4779cae468e3497a5ad1f4a1
- https://git.kernel.org/stable/c/c5dc463cc60eb26079b19607c9dbda76491dad05
Timeline
- Published
- Aug 10, 2026
- Last modified
- Oct 30, 2026
- NVD status
- Received