This vulnerability arises from the tls_gen_connection:handle_protocol_record/3 function in Erlang/OTP's ssl module, which rejects APPLICATION_DATA records during pre-handshake states only when acting as a server, but not when acting as a client. Consequently, a network-positioned attacker can inject plaintext APPLICATION_DATA records during the handshake to the client, which are buffered and delivered post-handshake as if authenticated. The attacker cannot observe or influence the connection, so the impact is limited to blind injection of unauthenticated bytes. The issue affects OTP versions from R13B03 before 27.3.4.14, from 28.0 before 28.5.0.3, and from 29.0 before 29.0.3, corresponding to ssl versions from 3.10.7 before 11.2.12.10, from 11.3 before 11.6.0.3, and from 11.7 before 11.7.3. OTP versions before R13B03 are of unknown status. TLS 1.3 support starting with OTP 22.0 is also affected, but the injection window is narrower for TLS 1.3 than earlier TLS versions.

An attacker positioned on the network can inject unauthenticated plaintext data into the TLS client during the handshake. This injected data is later processed by the client as if it were authenticated server data. However, the attacker cannot observe the client's responses or control the connection, limiting the impact to blind injection of data. This could potentially lead to application-level confusion or protocol desynchronization but does not allow direct data disclosure or connection hijacking.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor Erlang/OTP vendor advisories for updates and apply official patches once available. Until then, be aware of the risk of unauthenticated data injection during TLS handshake in affected versions.