CVE-2026-68118

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.

CVSS v3 8.2 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
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

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-10 13:19

Updated : 2026-08-23 13:16

NVD link : CVE-2026-68118

Mitre link : CVE-2026-68118

CVE.ORG link : CVE-2026-68118

JSON object : View

Products Affected

No product.

CWE

No CWE.

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