K90011301 : libssh2 vulnerabilities CVE-2019-3856, CVE-2019-3857, and CVE-2019-3863

Security Advisory Description

• CVE-2019-3856

An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 before 1.8.1 in the way keyboard prompt requests are parsed. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

• CVE-2019-3857

An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST packets with an exit signal are parsed. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

• CVE-2019-3863

A flaw was found in libssh2 before 1.8.1. A server could send a multiple keyboard interactive response messages whose total length are greater than unsigned char max characters. This value is used as an index to copy memory causing in an out of bounds memory write error.

Impact

For CVE-2019-3856 and CVE-2019-3857, a remote attacker may be able to execute code on the client system when a user connects to the server.

For CVE-2019-3863, an attacker may be able to initiate a response from the server in which the message length causes an out-of-bounds memory write.