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CVE PROGRAM SOURCE RECORD8.2 High

CVE-2026-68118

tcp: challenge ACK for non-exact RST in SYN-RECEIVED

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Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 282f23c6ee343126156dd41218b22ece96d747e3 to < c5dc463cc60eb26079b19607c9dbda76491dad05affected
  • 282f23c6ee343126156dd41218b22ece96d747e3 to < 8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49affected
  • 282f23c6ee343126156dd41218b22ece96d747e3 to < 0fe4636665d14a258de70b4f3e8248e6d42038f1affected
  • 282f23c6ee343126156dd41218b22ece96d747e3 to < 234f9ffbd9b2c1b24ec67200ea3cff07401bec48affected
  • 282f23c6ee343126156dd41218b22ece96d747e3 to < 22cec809b048495310f206d9abbcdbbfbdce3ae3affected
  • 282f23c6ee343126156dd41218b22ece96d747e3 to < a28c4fcbf774e23b4779cae468e3497a5ad1f4a1affected
  • 86791bbfe5ed7b275be040cfeff049a1624af1b7affected
  • 61f69dc4e40e41b0018f00fa4aeb23d3239556fbaffected
  • 34fb350281ced2a72707a5c0064f69992d440edbaffected
  • 3.0.58 to < 3.1affected
  • 3.2.37 to < 3.3affected
  • 3.4.25 to < 3.5affected

Linux Linux

Default version status: affected

  • 3.6affected
  • 0 to < 3.6unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.153 to ≤ 6.6.*unaffected
  • 6.12.105 to ≤ 6.12.*unaffected
  • 6.18.42 to ≤ 6.18.*unaffected
  • 7.1.6 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References