CVE-2024-39503 netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type
A race condition in the Linux kernel ipset module allows local attackers to trigger a use-after-free, potentially leading to code execution or privilege escalation.
- 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-2024-39503?
CVE-2024-39503 is a high-severity use after free vulnerability in Linux kernel, published on 12 Jul 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:
netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type
Lion Ackermann reported that there is a race condition between namespace cleanup in ipset and the garbage collection of the list:set type. The namespace cleanup can destroy the list:set type of sets while the gc of the set type is waiting to run in rcu cleanup. The latter uses data from the destroyed set which thus leads use after free. The patch contains the following parts:
- When destroying all sets, first remove the garbage collectors, then wait if needed and then destroy the sets. - Fix the badly ordered "wait then remove gc" for the destroy a single set case. - Fix the missing rcu locking in the list:set type in the userspace test case. - Use proper RCU list handlings in the list:set type.
The patch depends on c1193d9bbbd3 (netfilter: ipset: Add list flush to cancel_gc).
Which versions are affected by CVE-2024-39503?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-39503?
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-2024-39503 being exploited?
There is no known exploitation of CVE-2024-39503 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-39503, DEBIAN-CVE-2024-39503, GHSA-r75c-r77g-h7h2, UBUNTU-CVE-2024-39503.