x509: Fail CRL validity check if thisUpdate is in the future

src/libstrongswan/plugins/x509/x509_crl.c

@@ -546,7 +546,7 @@ METHOD(certificate_t, get_validity, bool,
 	{
 		*not_after = this->nextUpdate;
 	}
-	return (t <= this->nextUpdate);
+	return (t >= this->thisUpdate && t <= this->nextUpdate);
 }
 
 METHOD(certificate_t, get_encoding, bool,