The vulnerability arises in Go’s standard library crypto/tls when Encrypted Client Hello is used.‑ unencrypted portion of the client hello, a weakness that maps to CWE‑201 (Information Exposure). An attacker who can observe the traffic can therefore link the session to a specific client, undermining anonymity and potentially revealing information about the user’s location or identity.

All Go implementations that compile the standard library crypto/tls and enable Encrypted Client Hello in their TLS configurations are affected. No specific version polygons are listed, feature remains vulnerable until a patch is applied.

The CVSS score of 5.3 indicates moderate severity. Exploitation requires only passive below 1%, suggesting low likelihood of widespread exploitation at present, and the issue is not listed in CISA KEV. The primary vector is a network monitor positioned between client and anonymity or secrecy.