An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST packets with an exit status message and no payload are parsed. A remote attacker who compromises a SSH server may be able to cause a Denial of Service or read data in the client memory.

An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the _libssh2_packet_require and _libssh2_packet_requirev functions. A remote attacker who compromises a SSH server may be able to cause a Denial of Service or read data in the client memory.

A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. A malicious client could create channels without first performing authentication, resulting in unauthorized access.

The diffie_hellman_sha256 function in kex.c in libssh2 before 1.7.0 improperly truncates secrets to 128 or 256 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."

The (1) SSH_MSG_NEWKEYS and (2) SSH_MSG_KEXDH_REPLY packet handlers in package_cb.c in libssh before 0.6.5 do not properly validate state, which allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted SSH packet.

libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."

The kex_agree_methods function in libssh2 before 1.5.0 allows remote servers to cause a denial of service (crash) or have other unspecified impact via crafted length values in an SSH_MSG_KEXINIT packet.

Double free vulnerability in the ssh_packet_kexinit function in kex.c in libssh 0.5.x and 0.6.x before 0.6.4 allows remote attackers to cause a denial of service via a crafted kexinit packet.

The RAND_bytes function in libssh before 0.6.3, when forking is enabled, does not properly reset the state of the OpenSSL pseudo-random number generator (PRNG), which causes the state to be shared between children processes and allows local users to obtain sensitive information by leveraging a pid collision.

The publickey_from_privatekey function in libssh before 0.5.4, when no algorithm is matched during negotiations, allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a "Client: Diffie-Hellman Key Exchange Init" packet.