Medium severity · published Sep 4, 2026
CVE-2026-15937
Agent receiver certificate confusion allows authentication with a certificate issued for another endpoint
5.3
CVSS
0.2%
EPSS
No
On KEV
Description
Improper certificate validation in Checkmk <2.5.0p10 allows a relay and a push agent that share the same UUID to reuse each other's mTLS certificate to authenticate against agent receiver endpoints in either direction, because the endpoints do not verify that the certificate was issued by their own root certificate.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 14% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CH
Checkmk · Checkmk GmbH
2.5.0 before 2.5.0p10 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-15937
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-15937
checkmk.com
https://checkmk.com/werk/19735
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