CVE-2026-64530: Critical Vulnerability in Linux Kernel

Introduction

A critical vulnerability has been identified in the Linux kernel that may affect system security and stability. This vulnerability allows an attacker to potentially cause a use-after-free (UAF) condition, leading to undesirable system behavior.

What happened?

The vulnerability lies in how the Linux kernel handles packet classification in networking. Specifically, when the tcf_classify() function returns TC_ACT_CONSUMED, the network packet (skb) should not be manipulated again as it is no longer owned by the caller. However, the tcf_qevent_handle() function did not correctly handle this case, allowing the skb to be improperly manipulated, resulting in a use-after-free condition.

How does the vulnerability work?

When a network packet is processed and classified, if it is marked as consumed, it should not be touched again. The flaw occurs when the skb is returned to the caller as if classification had succeeded, allowing subsequent operations to be performed on an skb that is no longer owned. This can lead to memory corruption and ultimately unexpected system behavior.

What is the real impact?

The impact of this vulnerability is considered critical as it may allow an attacker to cause system crashes, potentially leading to denial of service or the execution of malicious code. Improper handling of network packets can affect the integrity and availability of the system.

Which versions are affected?

• linux kernel ≥ 5.15.148 < 5.15.212
• linux kernel ≥ 6.1.75 < 6.1.178
• linux kernel ≥ 6.6.14 < 6.6.145
• linux kernel ≥ 6.7.2 < 6.12.97
• linux kernel ≥ 6.13 < 6.18.40
• linux kernel ≥ 6.19 < 7.1.5

How to fix

1. Check your Linux kernel version using the uname -r command.
2. If your version is among the affected ones, update to a fixed version. Refer to the vendor documentation for information on secure versions.
3. Reboot the system after the update to ensure changes take effect.
4. Monitor kernel security advisories for future updates and patches.

Mitigation while updating

While an update is not possible, consider limiting network access and monitoring traffic for anomalous behavior. Additionally, disable features related to packet manipulation if applicable.

Conclusion

It is essential for system administrators and server owners to be aware of this vulnerability and take immediate action to update their systems. Security should be a priority to prevent potential exploits and ensure data integrity.