It's requesting 0x4000 (16384) bytes. Here's what the bytes in the heartbeat packet sent by the PoC mean: 0x18 TLS content type: heartbeat

It's requesting 0x4000 (16384) bytes. Here's what the bytes in the heartbeat packet sent by the PoC mean: 0x18 TLS content type: heartbeat [*] 0x03 0x02 protocol version: TLS 1.1 [RFC 4346, section A.1] 0x01 message type: heartbeat request [RFC 6520, section 3] 0x40 0x00 payload length: 16384 bytes [RFC 6520, section 4] This should be followed by a payload of that length, but if it isn't (as in the PoC) the vulnerable versions of OpenSSL will then carve it out of the heap to form the response packet - this is what leads to the data leakage. [*] see https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-5 https://www.iana.org/assignments/tls-parameters/tls-paramete...