A libssh2 security update has been released for Debian GNU/Linux 9 LTS.

DLA 2848-1: libssh2 security update

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Debian LTS Advisory DLA-2848-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Anton Gladky
December 17, 2021   https://wiki.debian.org/LTS
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Package : libssh2
Version : 1.7.0-1+deb9u2
CVE ID : CVE-2019-13115 CVE-2019-17498

Two issues have been discovered in libssh2, a client-side C library implementing
the SSH2 protocol:

CVE-2019-13115:
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.

CVE-2019-17498:
SSH_MSG_DISCONNECT logic in packet.c has an integer overflow in a bounds check,
enabling an attacker to specify an arbitrary (out-of-bounds) offset for a
subsequent memory read. A crafted 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.

For Debian 9 stretch, these problems have been fixed in version
1.7.0-1+deb9u2.

We recommend that you upgrade your libssh2 packages.

For the detailed security status of libssh2 please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/libssh2

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://wiki.debian.org/LTS