Time-of-check Time-of-use (TOCTOU) Race Condition in CoreDNS - CVE-2026-26017
Published: March 6, 2026
Vulnerability identifier: #VU123609
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N]
CVE-ID: CVE-2026-26017
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to bypass implemented security restrictions.
The vulnerability exists due to a race condition in the default execution order of plugins. A remote user can bypass implemented ACL restrictions and gain unauthorized access to protected systems. in multi-tenant Kubernetes clusters it is possible to bypass DNS-based segmentation and perform unauthorized service discovery and reconnaissance of restricted internal infrastructure.
Affected software
CoreDNS
openEuler
coredns
coredns-help
openEuler
coredns
coredns-help
How to mitigate CVE-2026-26017
Install updates from vendor's website.
CoreDNS - update to 1.14.2
coredns - addressed in versions 1.7.0-1.4, 1.7.0-1.6
coredns-help - addressed in versions 1.7.0-1.4, 1.7.0-1.6
coredns - addressed in versions 1.7.0-1.4, 1.7.0-1.6
coredns-help - addressed in versions 1.7.0-1.4, 1.7.0-1.6