Alert 42
TLS Alert 42 · bad_certificate
Recorded
TLS AlertDescription value 42 = bad_certificate in the IANA TLS Alerts registry and RFC 5246.
RFC 5246 section 7.2 names AlertDescription bad_certificate(42): a certificate was corrupt, or it contained signatures that did not verify. IANA TLS Alerts lists value 42 as bad_certificate. The same number remains in the TLS 1.3 alert space.
What it supports
An exact wire code in the TLS alert protocol. A certificate-integrity alert with a hard primary, not a press paraphrase.
What it does not
Not an OpenSSL internal X509 error remapping. Not certificate_expired (45) or unknown_ca (48). Not Adams.
ExactnessExact
Form42
UnitTLS alert code
Strengthhard
Hung26 September 2026