CVE-2024-27394 tcp: Fix Use-After-Free in tcp_ao_connect_init

What is CVE-2024-27394?

CVE-2024-27394 is a high-severity use after free vulnerability in Linux kernel, published on 9 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

tcp: Fix Use-After-Free in tcp_ao_connect_init

Since call_rcu, which is called in the hlist_for_each_entry_rcu traversal of tcp_ao_connect_init, is not part of the RCU read critical section, it is possible that the RCU grace period will pass during the traversal and the key will be free.

To prevent this, it should be changed to hlist_for_each_entry_safe.

Weakness: CWE-416

Which versions are affected by CVE-2024-27394?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-27394?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2024-27394 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-27394 exists.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2024-27394, DEBIAN-CVE-2024-27394, GHSA-q3rg-6598-285v, UBUNTU-CVE-2024-27394.