CVE-2026-52954 libceph: handle rbtree insertion error in decode_choose_args()
A malformed Ceph OSD map message triggers a kernel assertion failure, causing a denial of service in the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52954?
CVE-2026-52954 is a high-severity denial of service vulnerability in Linux kernel, published on 24 Jun 2026. 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:
libceph: handle rbtree insertion error in decode_choose_args()
A message of type CEPH_MSG_OSD_MAP contains an OSD map that itself contains a CRUSH map. The received CRUSH map may optionally contain choose_args that get decoded in decode_choose_args(). In this function, num_choose_arg_maps is read from the message, and a corresponding number of crush_choose_arg_maps gets decoded afterwards. Each crush_choose_arg_map has a choose_args_index, which serves as the key when inserting it into the choose_args rbtree of the decoded crush_map. If a (potentially corrupted) message contains two crush_choose_arg_maps with the same index, the assertion in insert_choose_arg_map() triggers a kernel BUG when trying to insert the second crush_choose_arg_map.
This patch fixes the issue by switching to the non-asserting rbtree insertion function and rejecting the message if the insertion fails.
[ idryomov: changelog ]
Which versions are affected by CVE-2026-52954?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52954?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-52954 being exploited?
There is no known exploitation of CVE-2026-52954 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90690, BELL-CVE-2026-52954, DEBIAN-CVE-2026-52954, GHSA-2rwm-p2mw-2gwh, ROOT-OS-DEBIAN-11-CVE-2026-52954, ROOT-OS-DEBIAN-12-CVE-2026-52954 and 3 more.