Public Date:
1687304: CVE-2019-3856 libssh2: Integer overflow in keyboard interactive handling resulting in out of bounds write
An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 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.

Find out more about CVE-2019-3856 from the MITRE CVE dictionary dictionary and NIST NVD.


This flaw was present in libssh2 packages included in Red Hat Virtualization Hypervisor and Management Appliance, however libssh2 in these hosts is never exposed to malicious clients or servers.

CVSS v3 metrics

CVSS3 Base Score 7.5
CVSS3 Base Metrics CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality High
Integrity Impact High
Availability Impact High

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux 8 (virt:rhel) RHSA-2019:1175 2019-05-14
Red Hat Enterprise Linux 7 (libssh2) RHSA-2019:0679 2019-03-28

Affected Packages State

Platform Package State
Red Hat Virtualization 4 rhvm-appliance Will not fix
Red Hat Virtualization 4 redhat-virtualization-host Will not fix
Red Hat Enterprise Linux 6 libssh2 Affected


Red Hat would like to thank the libssh2 project for reporting this issue. Upstream acknowledges Chris Coulson (Canonical Ltd.) as the original reporter.

External References

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