CVE-2023-53136 af_unix: fix struct pid leaks in OOB support

High 7.1 Published 2 May 2025 Updated 11 May 2026

A memory leak in the Linux kernel's af_unix OOB support allows attackers to exhaust kernel memory, potentially causing denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2023-53136?

CVE-2023-53136 is a high-severity memory corruption vulnerability in Linux kernel, published on 2 May 2025. 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:

af_unix: fix struct pid leaks in OOB support

syzbot reported struct pid leak [1].

Issue is that queue_oob() calls maybe_add_creds() which potentially holds a reference on a pid.

But skb->destructor is not set (either directly or by calling unix_scm_to_skb())

This means that subsequent kfree_skb() or consume_skb() would leak this reference.

In this fix, I chose to fully support scm even for the OOB message.

[1] BUG: memory leak unreferenced object 0xffff8881053e7f80 (size 128): comm "syz-executor242", pid 5066, jiffies 4294946079 (age 13.220s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff812ae26a>] alloc_pid+0x6a/0x560 kernel/pid.c:180 [<ffffffff812718df>] copy_process+0x169f/0x26c0 kernel/fork.c:2285 [<ffffffff81272b37>] kernel_clone+0xf7/0x610 kernel/fork.c:2684 [<ffffffff812730cc>] __do_sys_clone+0x7c/0xb0 kernel/fork.c:2825 [<ffffffff849ad699>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<ffffffff849ad699>] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 [<ffffffff84a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Weakness: CWE-125

Which versions are affected by CVE-2023-53136?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-53136?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2023-53136 being exploited?

There is no known exploitation of CVE-2023-53136 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2023-53136, DEBIAN-CVE-2023-53136, GHSA-vh39-pjjg-4hv4, UBUNTU-CVE-2023-53136.