CVE-2021-47123 io_uring: fix ltout double free on completion race
A race condition in the Linux kernel io_uring subsystem allows a double free leading to use-after-free, potentially enabling local privilege escalation or code execution.
- 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-2021-47123?
CVE-2021-47123 is a high-severity use after free vulnerability in Linux kernel, published on 15 Mar 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:
io_uring: fix ltout double free on completion race
Always remove linked timeout on io_link_timeout_fn() from the master request link list, otherwise we may get use-after-free when first io_link_timeout_fn() puts linked timeout in the fail path, and then will be found and put on master's free.
Which versions are affected by CVE-2021-47123?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47123?
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-2021-47123 being exploited?
There is no known exploitation of CVE-2021-47123 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as GHSA-j642-rp5q-w8w9, UBUNTU-CVE-2021-47123.