USN-5308-1: libssh2 vulnerabilities

Releases

• Ubuntu 16.04 ESM

Packages

• libssh2 - Client-side C library implementing the SSH2 protocol

Details

It was discovered that libssh2 mishandled certain input. If libssh2 were
used to connect to a malicious or compromised SSH server, a remote,
unauthenticated attacker could possibly execute arbitrary code on the client
system. (CVE-2019-3855)

It was discovered that libssh2 incorrectly handled prompt requests. A
remote attacker could possibly use this issue to execute arbitrary code.
(CVE-2019-3856)

It was discovered that libssh2 incorrectly handled SSH_MSG_CHANNEL_REQUEST
packets. A remote attacker could possibly use this issue to execute
arbitrary code, cause a denial of service, or obtain sensitive information.
(CVE-2019-3857, CVE-2019-3862)

It was discovered that libssh2 incorrectly handled specially crafted SFTP
packets. A remote attacker could possibly use this issue to cause a denial
of service or obtain sensitive information. (CVE-2019-3858)

It was discovered that libssh2 incorrectly handled certain specially
crafted packets. A remote attacker could possibly use this issue to cause a
denial of service or obtain sensitive information. (CVE-2019-3859)

It was discovered that libssh2 incorrectly handled SFTP packets with empty
payloads. A remote attacker could possibly use this issue to cause a denial
of service or obtain sensitive information. (CVE-2019-3860)

It was discovered that libssh2 incorrectly handled padding values in SSH
packets. A remote attacker could possibly use this issue to cause a denial
of service or obtain sensitive information. (CVE-2019-3861)

It was discovered that libssh2 incorrectly handled interactive response
messages length. A remote attacker could possibly use this issue to execute
arbitrary code. (CVE-2019-3863)

It was discovered that libssh2 incorrectly handled the Diffie Hellman key
exchange. A remote attacker could possibly use this issue to cause a denial
of service or obtain sensitive information. (CVE-2019-13115)

It was discovered that libssh2 incorrectly handled bound checks in
SSH_MSG_DISCONNECT. A remote attacker could possibly use this issue to
cause a denial of service or obtain sensitive information. (CVE-2019-17498)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 16.04

• libssh2-1 - 1.5.0-2ubuntu0.1+esm1
  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References

• CVE-2019-3863
• CVE-2019-3862
• CVE-2019-13115
• CVE-2019-3861
• CVE-2019-3855
• CVE-2019-3859
• CVE-2019-3857
• CVE-2019-3858
• CVE-2019-17498
• CVE-2019-3860
• CVE-2019-3856