CVE-2025-64998Network attack vector

Session hijacking via synchronized cookie-signing secret

Published Mar 24, 2026 · Updated Mar 24, 2026

Credential exposure in Checkmk before 2.4.0p23 and 2.3.0p45, and in 2.2.0, allows remote authenticated users to hijack sessions. Distributed configuration synchronization copies the central site’s session-signing secret to remote sites, while legacy user synchronization can also expose a valid session ID. An administrator of a config-sync-enabled remote site can combine both values to forge a valid cookie and assume an existing central-site session.

CVSS severity7.3
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Credential exposure in Checkmk before 2.4.0p23 and 2.3.0p45, and in 2.2.0, allows remote authenticated users to hijack sessions. Distributed configuration synchronization copies the central site’s session-signing secret to remote sites, while legacy user synchronization can also expose a valid session ID. An administrator of a config-sync-enabled remote site can combine both values to forge a valid cookie and assume an existing central-site session.

The record

CVE
CVE-2025-64998
Published
Mar 24, 2026
Updated
Mar 24, 2026
Vendor
Checkmk GmbH
Product
Checkmk
Classifications
CWE-522, T1606.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.2.0
  2. Affected versionversion=2.3.0 <2.3.0p45
  3. Affected versionversion=2.4.0 <2.4.0p23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Checkmk GmbH · Checkmkversion=2.2.0; version=2.3.0 <2.3.0p45; version=2.4.0 <2.4.0p23

Published CVSS scores

7.3Checkmk GmbHCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
T1606.001Forge Web Credentials: Web Cookies

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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