Race condition in Linux kernel - CVE-2026-64024

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Main Vulnerability Database Vulnerabilities #VU138620

Race condition in Linux kernel - CVE-2026-64024

Published: July 20, 2026


Vulnerability identifier: #VU138620
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64024
CWE-ID: CWE-362
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to predict TCP initial sequence numbers.

The vulnerability exists due to improper state management in the Linux kernel TCP input path when processing TCP packets that transition from TIME_WAIT handling and are later dropped before request processing. A remote attacker can send packets that trigger these drop paths and then send a subsequent SYN on the same CPU to predict TCP initial sequence numbers.

The issue occurs because a non-zero TIME_WAIT-derived ISN can remain stored after several packet-drop conditions, including policy, filter, checksum, and header validation failures.


Affected software

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-64024

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

External References

Related Security Bulletins