# CVE-2026-23220: ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths

> A flaw in the Linux kernel ksmbd module allows remote attackers to cause a denial of service via an infinite loop triggered by failed signature verification.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Feb 2026
- **Updated:** 2 Jun 2026
- **Also known as:** BELL-CVE-2026-23220, DEBIAN-CVE-2026-23220, GHSA-9wwr-2jh3-482p, ROOT-OS-DEBIAN-12-CVE-2026-23220, ROOT-OS-UBUNTU-2204-CVE-2026-23220, ROOT-OS-UBUNTU-2404-CVE-2026-23220, UBUNTU-CVE-2026-23220

## What is CVE-2026-23220?

CVE-2026-23220 is a medium-severity denial of service vulnerability in Linux kernel, published on 18 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:

ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths

The problem occurs when a signed request fails smb2 signature verification
check. In __process_request(), if check_sign_req() returns an error,
set_smb2_rsp_status(work, STATUS_ACCESS_DENIED) is called.
set_smb2_rsp_status() set work->next_smb2_rcv_hdr_off as zero. By resetting
next_smb2_rcv_hdr_off to zero, the pointer to the next command in the chain
is lost. Consequently, is_chained_smb2_message() continues to point to
the same request header instead of advancing. If the header's NextCommand
field is non-zero, the function returns true, causing __handle_ksmbd_work()
to repeatedly process the same failed request in an infinite loop.
This results in the kernel log being flooded with "bad smb2 signature"
messages and high CPU usage.

This patch fixes the issue by changing the return value from
SERVER_HANDLER_CONTINUE to SERVER_HANDLER_ABORT. This ensures that
the processing loop terminates immediately rather than attempting to
continue from an invalidated offset.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-23220?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23220?

Apply the vendor's patch.

## Is CVE-2026-23220 being exploited?

There is no known exploitation of CVE-2026-23220 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-2026-23220 and fix it if it is affected.

What it is: CVE-2026-23220 is a medium-severity denial of service vulnerability in Linux kernel, published on 18 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-2026-23220 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-2026-23220/ (Markdown: https://insights.sbomify.com/CVE-2026-23220/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23220
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23220
- OSV: https://osv.dev/vulnerability/CVE-2026-23220

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23220/
Summaries are generated and may contain mistakes; the official description above is the record.