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GHSA-7jrq-q4pq-rhm6
No affected components available
Summary
The trustedCertPool() function in the TLS configuration only parses the first PEM block from CA certificate files. When a CA bundle contains multiple certificates (e.g., intermediate + root CA), only the first certificate is loaded. This silently breaks certificate chain validation for mTLS.
Impact
In deployments using mTLS with certificate chains (intermediate CA + root CA bundles), legitimate clients with properly chained certificates are rejected with x509: certificate signed by unknown authority. This degrades the security posture by making mTLS unusable with standard CA chain configurations, potentially forcing operators to disable client certificate verification.
All versions using TLS with trustedCaFile configuration are affected.
Details
In common/security/tls.go, the trustedCertPool() method calls pem.Decode() only once, processing a single PEM block. The remaining bytes (containing additional certificates) are silently discarded. Additionally, the error return from pem.Decode is ignored, so a corrupted CA file results in an empty certificate pool without any error.
Patches
Fixed by iterating over all PEM blocks in the file, parsing each CERTIFICATE block, and returning an error if no valid certificates are found.
Workarounds
Use CA files containing only a single certificate (the direct issuer of client certificates, not a chain).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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