Failed. Ee Key Is Too Small — Cisco Asa Certificate Validation

Upon investigation, the team found that the certificate chain installed on the ASA was incomplete. The ASA had the new server certificate (2048-bit) but still referenced an old, cached intermediate CA certificate that contained a 1024-bit public key.

The ASA, when building the chain, used the older intermediate CA cert because it had a matching issuer name. It then checked the —but in the ASA’s validation logic, “EE key” in this context meant the public key of the end entity certificate presented by the client ? No, actually the error is misleading: it refers to the server certificate’s own key being too small ? Wait, not exactly. cisco asa certificate validation failed. ee key is too small

A mid-sized company was migrating its VPN remote access from an old Cisco ASA 5510 to a newer ASA 5508-X. The security team decided to renew the SSL certificate for the AnyConnect VPN endpoint, moving from a 1024-bit RSA certificate to a more secure 2048-bit one. The certificate was issued by their internal Microsoft CA. Upon investigation, the team found that the certificate

One Monday morning, users started reporting that their AnyConnect VPN connections were failing. The ASA logs showed: certificate validation failed. ee key is too small The IT team was puzzled—they had just installed a brand-new 2048-bit certificate. Why would the ASA reject it as “too small”? It then checked the —but in the ASA’s

The ASA was configured for client certificate authentication (accidentally left on from old config) and some remote users were still using old 512-bit or 1024-bit software certificates on their laptops. When those users connected, the ASA attempted to validate their client cert and rejected it because the key size was too small. The confusing part was that the error message appeared in the log at the same time as the new server cert was installed, but it was unrelated.