# CVE-2026-22991: libceph: make free_choose_arg_map() resilient to partial allocation

> A NULL pointer dereference in the Linux kernel's libceph module can cause a system crash when handling partial memory allocations.

- **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:** 23 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-78470, BELL-CVE-2026-22991, DEBIAN-CVE-2026-22991, GHSA-953j-p37p-r755, ROOT-OS-DEBIAN-11-CVE-2026-22991, ROOT-OS-DEBIAN-12-CVE-2026-22991, ROOT-OS-DEBIAN-13-CVE-2026-22991, ROOT-OS-UBUNTU-2204-CVE-2026-22991, ROOT-OS-UBUNTU-2404-CVE-2026-22991, UBUNTU-CVE-2026-22991

## What is CVE-2026-22991?

CVE-2026-22991 is a high-severity vulnerability in Linux kernel, published on 23 Jan 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: make free_choose_arg_map() resilient to partial allocation

free_choose_arg_map() may dereference a NULL pointer if its caller fails
after a partial allocation.

For example, in decode_choose_args(), if allocation of arg_map->args
fails, execution jumps to the fail label and free_choose_arg_map() is
called. Since arg_map->size is updated to a non-zero value before memory
allocation, free_choose_arg_map() will iterate over arg_map->args and
dereference a NULL pointer.

To prevent this potential NULL pointer dereference and make
free_choose_arg_map() more resilient, add checks for pointers before
iterating.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-22991?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-22991?

Apply the vendor's patch.

## Is CVE-2026-22991 being exploited?

There is no known exploitation of CVE-2026-22991 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-2026-22991 and fix it if it is affected.

What it is: CVE-2026-22991 is a high-severity vulnerability in Linux kernel, published on 23 Jan 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-2026-22991 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-2026-22991/ (Markdown: https://insights.sbomify.com/CVE-2026-22991/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-22991
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-22991
- OSV: https://osv.dev/vulnerability/CVE-2026-22991

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-22991/
Summaries are generated and may contain mistakes; the official description above is the record.