CVE-2026-23247

Updated on 18 Mar 2026

Severity

5.5 Medium severity

Details

CVSS score
5.5
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Overview

About vulnerability

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.

Details

Affected packages:
linux @ 5.4.0 (+8 more)

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.

Fixes