Scientists have identified weaknesses in the way popular cryptographic algorithm Diffie-Hellman key exchange is deployed – notably, they discovered an attack that could enable the reading and modifying of data passed over TLS connections.

The attack can be used by a MITM attacker to downgrade TLS connections to 512-bit export-grade cryptography that is weaker and easier to crack, thus enabling the reading and modifying of data. The attack is similar to the FREAK attack, except it attacks Diffie-Hellman key exchange as opposed to RSA key exchange, and is the result of a flaw in TLS protocol.