8.2

CVE-2026-68118: linux Improper Input Validation

CVSS: 8.2v3.1HighReceived
AliasesUBUNTU-CVE-2026-68118DEBIAN-CVE-2026-68118
Published 10-08-2026Last modified 19-10-2026
Open JSON

Vulnerability summary

CVE-2026-68118 is a high (CVSS 8.2) Improper Input Validation vulnerability in linux. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 31.8% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.2/10
010
High · v3.1 (CVE.org)
EPSS score
0.39%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 9 · Related 7
MGASA-2026-0336MGASA-2026-0337USN-8886-1USN-8887-1USN-8887-2USN-8887-3

Timeline

  1. 10-08-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.39%

Chance of exploitation in the next 30 days

Percentile

32%

Versus all other CVEs

30-day change

0.00 pp

From 0.39% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.39%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu169 products
  • linuxAll versions (No fix recorded) | < 7.0.0-38.38
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 7.0.0-1014.14
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian2 products
  • linuxAll versions (No fix recorded) | < 6.12.105-1 | < 7.1.6-1
  • linux-6.12< 6.12.107-1~deb12u1
Linux1 product
  • linux≥ 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 | 3.6

3 vendors · 172 products

References

16 links
Show all 16 references