CVE-2024-53206 tcp: Fix use-after-free of nreq in reqsk_timer_handler().

What is CVE-2024-53206?

CVE-2024-53206 is a critical use after free vulnerability in Linux kernel, published on 27 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

tcp: Fix use-after-free of nreq in reqsk_timer_handler().

The cited commit replaced inet_csk_reqsk_queue_drop_and_put() with __inet_csk_reqsk_queue_drop() and reqsk_put() in reqsk_timer_handler().

Then, oreq should be passed to reqsk_put() instead of req; otherwise use-after-free of nreq could happen when reqsk is migrated but the retry attempt failed (e.g. due to timeout).

Let's pass oreq to reqsk_put().

Weakness: CWE-416

Which versions are affected by CVE-2024-53206?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-53206?

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-2024-53206 being exploited?

There is no known exploitation of CVE-2024-53206 in the wild and no public exploit code.

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 AZL-55564, BELL-CVE-2024-53206, DEBIAN-CVE-2024-53206, GHSA-hx9w-rm9x-mqpr, UBUNTU-CVE-2024-53206.