CVE-2026-23247 Affecting kernel6.18 package, versions <1:6.18.20-20.229.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.01% (4th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618-16348317
  • published3 May 2026
  • disclosed18 Mar 2026

Introduced: 18 Mar 2026

CVE-2026-23247  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18 to version 1:6.18.20-20.229.amzn2023 or higher.
This issue was patched in ALAS2023-2026-1596.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18 package and not the kernel6.18 package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

tcp: secure_seq: add back ports to TS offset

This reverts 28ee1b746f49 ("secure_seq: downgrade to per-host timestamp offsets")

tcp_tw_recycle went away in 2017.

Zhouyan Deng reported off-path TCP source port leakage via SYN cookie side-channel that can be fixed in multiple ways.

One of them is to bring back TCP ports in TS offset randomization.

As a bonus, we perform a single siphash() computation to provide both an ISN and a TS offset.

CVSS Base Scores

version 3.1