Published: 16 July 2019
In libssh2 before 1.9.0, kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c has an integer overflow that could lead to an out-of-bounds read in the way packets are read from the server. A remote attacker who compromises a SSH server may be able to disclose sensitive information or cause a denial of service condition on the client system when a user connects to the server. This is related to an _libssh2_check_length mistake, and is different from the various issues fixed in 1.8.1, such as CVE-2019-3855.
From the Ubuntu security team
It was discovered that libssh2 incorrectly handled Diffie Hellman key exchange. A remote attacker could possibly use this issue to cause a denial of service or obtain sensitive information.
CVSS 3 base score: 8.1
Launchpad, Ubuntu, Debian
|Ubuntu 21.04 (Hirsute Hippo)||
|Ubuntu 20.04 LTS (Focal Fossa)||
|Ubuntu 18.04 LTS (Bionic Beaver)||
|Ubuntu 16.04 ESM (Xenial Xerus)||
(end of standard support, was needed)
|Ubuntu 14.04 ESM (Trusty Tahr)||