CVE-2023-0240 Use after free in io_uring in the Linux Kernel

What is CVE-2023-0240?

CVE-2023-0240 is a high-severity use after free vulnerability in Linux kernel, published on 30 Jan 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

There is a logic error in io_uring's implementation which can be used to trigger a use-after-free vulnerability leading to privilege escalation.

In the io_prep_async_work function the assumption that the last io_grab_identity call cannot return false is not true, and in this case the function will use the init_cred or the previous linked requests identity to do operations instead of using the current identity. This can lead to reference counting issues causing use-after-free. We recommend upgrading past version 5.10.161.

Weakness: CWE-416

Which versions are affected by CVE-2023-0240?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2023-0240?

Upgrade to a fixed version.

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-2023-0240 being exploited?

There is no known exploitation of CVE-2023-0240 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 DEBIAN-CVE-2023-0240, GHSA-rr76-fj9v-7w82, UBUNTU-CVE-2023-0240.