Improper Certificate Validation in etcd - CVE-2026-59818
Published: July 24, 2026
Vulnerability identifier: #VU139351
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-59818
CWE-ID: CWE-295
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: CoreOS
Affected software:
etcd
etcd
Detailed vulnerability description
The vulnerability allows a remote user to bypass certificate revocation list enforcement and authenticate with a revoked certificate.
The vulnerability exists due to improper certificate validation in the gRPC client listener when `--listen-client-http-urls` is configured to split HTTP and gRPC client endpoints onto separate listeners. A remote privileged user can present a revoked certificate over gRPC to bypass certificate revocation list enforcement and authenticate with a revoked certificate.
The HTTP endpoint correctly rejects revoked certificates, but the gRPC listener continues to accept them in this configuration.
How to mitigate CVE-2026-59818
Install security update from vendor's website.