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8.2
HIGH CVSS 3.1
CVE-2026-68118
tcp: challenge ACK for non-exact RST in SYN-RECEIVED
Overview
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.

Details
INFO

Published Date :

Aug. 10, 2026, 1:19 p.m.

Last Modified :

Aug. 17, 2026, 5:18 a.m.

Remotely Exploit :

Yes !

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Impact
Affected Products

The following products are affected by CVE-2026-68118 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
Implement RFC 9293 challenge ACK logic for non-exact RSTs in SYN-RECEIVED state.
  • Apply RFC 5961 reset check before ACK validation.
  • Factor challenge ACK quota out of tcp_send_challenge_ack().
  • Use request socket's send_ack() callback.
  • Use request socket's out-of-window ACK timestamp.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-68118.

URL Resource
https://git.kernel.org/stable/c/22cec809b048495310f206d9abbcdbbfbdce3ae3
https://git.kernel.org/stable/c/234f9ffbd9b2c1b24ec67200ea3cff07401bec48
https://git.kernel.org/stable/c/a28c4fcbf774e23b4779cae468e3497a5ad1f4a1
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-68118 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-68118 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-68118 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-68118 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 17, 2026

    Action Type Old Value New Value
    Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '234f9ffbd9b2c1b24ec67200ea3cff07401bec48', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '22cec809b048495310f206d9abbcdbbfbdce3ae3', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': 'a28c4fcbf774e23b4779cae468e3497a5ad1f4a1', 'versionType': 'git'}, {'status': 'affected', 'version': '86791bbfe5ed7b275be040cfeff049a1624af1b7', 'versionType': 'git'}, {'status': 'affected', 'version': '61f69dc4e40e41b0018f00fa4aeb23d3239556fb', 'versionType': 'git'}, {'status': 'affected', 'version': '34fb350281ced2a72707a5c0064f69992d440edb', 'versionType': 'git'}, {'status': 'affected', 'version': '3.0.58', 'lessThan': '3.1', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.2.37', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.25', 'lessThan': '3.5', 'versionType': 'semver'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '234f9ffbd9b2c1b24ec67200ea3cff07401bec48', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '22cec809b048495310f206d9abbcdbbfbdce3ae3', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': 'a28c4fcbf774e23b4779cae468e3497a5ad1f4a1', 'versionType': 'git'}, {'status': 'affected', 'version': '86791bbfe5ed7b275be040cfeff049a1624af1b7', 'versionType': 'git'}, {'status': 'affected', 'version': '61f69dc4e40e41b0018f00fa4aeb23d3239556fb', 'versionType': 'git'}, {'status': 'affected', 'version': '34fb350281ced2a72707a5c0064f69992d440edb', 'versionType': 'git'}, {'status': 'affected', 'version': '3.0.58', 'lessThan': '3.1', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.2.37', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.25', 'lessThan': '3.5', 'versionType': 'semver'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'affected'}]
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 13, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 10, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '234f9ffbd9b2c1b24ec67200ea3cff07401bec48', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': '22cec809b048495310f206d9abbcdbbfbdce3ae3', 'versionType': 'git'}, {'status': 'affected', 'version': '282f23c6ee343126156dd41218b22ece96d747e3', 'lessThan': 'a28c4fcbf774e23b4779cae468e3497a5ad1f4a1', 'versionType': 'git'}, {'status': 'affected', 'version': '86791bbfe5ed7b275be040cfeff049a1624af1b7', 'versionType': 'git'}, {'status': 'affected', 'version': '61f69dc4e40e41b0018f00fa4aeb23d3239556fb', 'versionType': 'git'}, {'status': 'affected', 'version': '34fb350281ced2a72707a5c0064f69992d440edb', 'versionType': 'git'}, {'status': 'affected', 'version': '3.0.58', 'lessThan': '3.1', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.2.37', 'lessThan': '3.3', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.25', 'lessThan': '3.5', 'versionType': 'semver'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.18.42', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/tcp.h', 'net/ipv4/tcp_input.c', 'net/ipv4/tcp_minisocks.c'], 'defaultStatus': 'affected'}]
    Added 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.
    Added Reference https://git.kernel.org/stable/c/22cec809b048495310f206d9abbcdbbfbdce3ae3
    Added Reference https://git.kernel.org/stable/c/234f9ffbd9b2c1b24ec67200ea3cff07401bec48
    Added Reference https://git.kernel.org/stable/c/a28c4fcbf774e23b4779cae468e3497a5ad1f4a1
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 8.2
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