# CVE-2026-52955: libceph: Fix potential out-of-bounds access in crush_decode()

> An attacker can trigger an out-of-bounds access in the Linux kernel's Ceph client by sending a malformed CRUSH map, potentially leading to code execution or system crash.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-90500, BELL-CVE-2026-52955, DEBIAN-CVE-2026-52955, GHSA-jh5w-4gpm-r5xw, ROOT-OS-DEBIAN-11-CVE-2026-52955, ROOT-OS-DEBIAN-12-CVE-2026-52955, ROOT-OS-UBUNTU-2204-CVE-2026-52955, ROOT-OS-UBUNTU-2404-CVE-2026-52955, UBUNTU-CVE-2026-52955

## What is CVE-2026-52955?

CVE-2026-52955 is a critical memory corruption 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: Fix potential out-of-bounds access in crush_decode()

A message of type CEPH_MSG_OSD_MAP containing a crush map with at least
one bucket has two fields holding the bucket algorithm. If the values
in these two fields differ, an out-of-bounds access can occur. This is
the case because the first algorithm field (alg) is used to allocate
the correct amount of memory for a bucket of this type, while the second
algorithm field inside the bucket (b->alg) is used in the subsequent
processing.

This patch fixes the issue by adding a check that compares alg and
b->alg and aborts the processing in case they differ. Furthermore,
b->alg is set to 0 in this case, because the destruction of the crush
map also uses this field to determine the bucket type, which can again
result in an out-of-bounds access when trying to free the memory pointed
to by the fields of the bucket. To correctly free the memory allocated
for the bucket in such a case, the corresponding call to kfree is moved
from the algorithm-specific crush_destroy_bucket functions to the
generic crush_destroy_bucket().

Weakness: CWE-125 (Out-of-bounds Read), CWE-131 (Incorrect Calculation of Buffer Size)

## Which versions are affected by CVE-2026-52955?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-52955?

Apply the vendor's patch.

## Is CVE-2026-52955 being exploited?

There is no known exploitation of CVE-2026-52955 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-2026-52955 and fix it if it is affected.

What it is: CVE-2026-52955 is a critical memory corruption 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-2026-52955 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-2026-52955/ (Markdown: https://insights.sbomify.com/CVE-2026-52955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52955
- OSV: https://osv.dev/vulnerability/CVE-2026-52955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52955/
Summaries are generated and may contain mistakes; the official description above is the record.