Release Summary:

Fixed a validation issue in s2n_connection_deserialize() where malformed protocol version bytes could result in invalid connection state and inconsistent TLS behavior.

Resolved issues:

Fixes a validation issue in s2n_connection_deserialize() where malformed protocol version bytes could result in invalid connection state and inconsistent TLS behavior.

The issue is that a user controlling serialized connection data could provide malformed protocol version bytes that, when deserialized and used in the connection, would result in invalid protocol versions outside the valid TLS range (30-34). These invalid values can trigger unexpected code paths and cause inconsistent TLS behavior where the connection operates with protocol versions that don't correspond to any legitimate TLS version.

Description of changes:

Added protocol version validation in s2n_connection_deserialize_parse() to ensure deserialized protocol versions are within the valid TLS range (S2N_SSLv3 to s2n_highest_protocol_version(S2N_TLS13))

Call-outs:

This is not considered a security issue. Users are responsible for protecting serialized connection data as documented in Connection Serialization Usage Guide. The serialized data contains sensitive cryptographic material and must be protected by the application.

We also have API documentation for proper usage: s2n_connection_serialize() and s2n_connection_deserialize()

Testing:

Added unit tests for protocol validation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.