# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Jun 2026
- **Updated:** 19 Oct 2026
- **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, ROOT-OS-UBUNTU-2204-CVE-2026-52954, ROOT-OS-UBUNTU-2404-CVE-2026-52954, UBUNTU-CVE-2026-52954

## 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 ]

Weakness: CWE-617 (Reachable Assertion), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-52954?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52954?

Apply the vendor's patch.

## 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52954 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-52954 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-52954/ (Markdown: https://insights.sbomify.com/CVE-2026-52954/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52954
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52954
- OSV: https://osv.dev/vulnerability/CVE-2026-52954

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52954/
Summaries are generated and may contain mistakes; the official description above is the record.