# CVE-2025-64998: Session hijacking via exposed session signing secret in distributed Checkmk setups

> Remote site administrators can hijack central site sessions by forging cookies due to exposed signing secrets in distributed Checkmk setups.

- **Severity:** High 7.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 24 Mar 2026
- **Updated:** 25 Mar 2026
- **Also known as:** GHSA-6642-x6x4-g343, UBUNTU-CVE-2025-64998

## What is CVE-2025-64998?

CVE-2025-64998 is a high-severity vulnerability in Checkmk Checkmk, published on 24 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Exposure of session signing secret in Checkmk <2.4.0p23, <2.3.0p45 and 2.2.0 allows an administrator of a remote site with config sync enabled to hijack sessions on the central site by forging session cookies.

Weakness: CWE-522 (Insufficiently Protected Credentials)

## Which versions are affected by CVE-2025-64998?

It affects 1 product.


Products: Checkmk Checkmk.

## How do I fix CVE-2025-64998?

No fix has been published for CVE-2025-64998 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-64998 being exploited?

There is no known exploitation of CVE-2025-64998 in the wild and no public exploit code.

## Other vulnerabilities in Checkmk Checkmk

- [CVE-2025-39666](https://insights.sbomify.com/CVE-2025-39666/): omd: Local privilege escalation when executing omd commands as root (critical 9.3)
- [CVE-2024-8606](https://insights.sbomify.com/CVE-2024-8606/): Fix 2FA bypass via RestAPI (critical 9.2)
- [CVE-2022-46836](https://insights.sbomify.com/CVE-2022-46836/): PHP code injection in watolib (critical 9.1)
- [CVE-2025-32919](https://insights.sbomify.com/CVE-2025-32919/): Privilege Escalation in Windows License plugin for Checkmk Windows Agent (high 8.8)
- [CVE-2024-28827](https://insights.sbomify.com/CVE-2024-28827/): Privilege escalation in Windows agent (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-64998 and fix it if it is affected.

What it is: CVE-2025-64998 is a high-severity vulnerability in Checkmk Checkmk, published on 24 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-64998 in the wild and no public exploit code.

Affected product: Checkmk Checkmk. 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-2025-64998/ (Markdown: https://insights.sbomify.com/CVE-2025-64998/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-64998
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-64998
- OSV: https://osv.dev/vulnerability/CVE-2025-64998

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-64998/
Summaries are generated and may contain mistakes; the official description above is the record.