# CVE-2026-23183: cgroup/dmem: fix NULL pointer dereference when setting max

> A local attacker with high privileges can cause a kernel crash by writing invalid data to the cgroup dmem max file.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Feb 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23183, DEBIAN-CVE-2026-23183, GHSA-q6cr-hchj-9qvc, UBUNTU-CVE-2026-23183

## What is CVE-2026-23183?

CVE-2026-23183 is a vulnerability in Linux, published on 14 Feb 2026. 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:

cgroup/dmem: fix NULL pointer dereference when setting max

An issue was triggered:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: Oops: 0000 [#1] SMP NOPTI
 CPU: 15 UID: 0 PID: 658 Comm: bash Tainted: 6.19.0-rc6-next-2026012
 Tainted: [O]=OOT_MODULE
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
 RIP: 0010:strcmp+0x10/0x30
 RSP: 0018:ffffc900017f7dc0 EFLAGS: 00000246
 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888107cd4358
 RDX: 0000000019f73907 RSI: ffffffff82cc381a RDI: 0000000000000000
 RBP: ffff8881016bef0d R08: 000000006c0e7145 R09: 0000000056c0e714
 R10: 0000000000000001 R11: ffff888107cd4358 R12: 0007ffffffffffff
 R13: ffff888101399200 R14: ffff888100fcb360 R15: 0007ffffffffffff
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000000 CR3: 0000000105c79000 CR4: 00000000000006f0
 Call Trace:
  <TASK>
  dmemcg_limit_write.constprop.0+0x16d/0x390
  ? __pfx_set_resource_max+0x10/0x10
  kernfs_fop_write_iter+0x14e/0x200
  vfs_write+0x367/0x510
  ksys_write+0x66/0xe0
  do_syscall_64+0x6b/0x390
  entry_SYSCALL_64_after_hwframe+0x76/0x7e
 RIP: 0033:0x7f42697e1887

It was trriggered setting max without limitation, the command is like:
"echo test/region0 > dmem.max". To fix this issue, add check whether
options is valid after parsing the region_name.

## Which versions are affected by CVE-2026-23183?


## How do I fix CVE-2026-23183?

Apply the vendor's patch.

## Is CVE-2026-23183 being exploited?

There is no known exploitation of CVE-2026-23183 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23183 and fix it if it is affected.

What it is: CVE-2026-23183 is a vulnerability in Linux, published on 14 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-23183 in the wild and no public exploit code.

Affected product: Linux. 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-2026-23183/ (Markdown: https://insights.sbomify.com/CVE-2026-23183/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23183
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23183
- OSV: https://osv.dev/vulnerability/CVE-2026-23183

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23183/
Summaries are generated and may contain mistakes; the official description above is the record.