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.
- 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
- None listed
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
Which versions are affected by CVE-2025-64998?
It affects 1 product.
Products include 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 omd: Local privilege escalation when executing omd commands as root
- CVE-2024-8606 Fix 2FA bypass via RestAPI
- CVE-2022-46836 PHP code injection in watolib
- CVE-2025-32919 Privilege Escalation in Windows License plugin for Checkmk Windows Agent
- CVE-2024-28827 Privilege escalation in Windows agent
Sources
Also known as GHSA-6642-x6x4-g343, UBUNTU-CVE-2025-64998.