crypto/x509: CPU denial of service in chain validation

[dmitshur]

Package crypto/x509 parses and validates X.509-encoded keys and certificates. It's supposed to handle certificate chains provided by an attacker with reasonable resource use.

The crypto/x509 package does not limit the amount of work performed for each chain verification, which might allow attackers to craft pathological inputs leading to a CPU denial of service. Go TLS servers accepting client certificates and TLS clients verifying certificates are affected.

Thanks to Netflix for discovering and reporting this issue.

This issue is CVE-2018-16875.

[FiloSottile]

Fixed in Go 1.11.3 by df52396.
Fixed in Go 1.10.6 by 0a4a37f.

[gopherbot]

Change https://golang.org/cl/154105 mentions this issue: crypto/x509: limit number of signature checks for each verification