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.
Acknowledgments: Name: the libssh2 project Upstream: Chris Coulson (Canonical Ltd.)
Function userauth_keyboard_interactive() in userauth.c sums a set of values without checking for integer overflow. The result is then used to allocate memory and to copy attacker-controlled strings later on. If the integer overflow happens, writes can happen out of bounds, possibly allowing an attacker to execute code remotely.
The attacker needs to: - trick the user to connect to a malicious server or - trick the user to connect to a compromised server or - intercept and modify the traffic For these reasons User Interaction (UI) is set to Required(R) and Attack Complexity (AC) is set to High (H).
Upstream patch: https://github.com/libssh2/libssh2/commit/dc109a7f518757741590bb993c0c8412928ccec2
Statement: 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.
Reference: https://www.openwall.com/lists/oss-security/2019/03/18/3 Upstream Patch: https://libssh2.org/1.8.0-CVE/CVE-2019-3863.txt
External References: https://www.libssh2.org/CVE-2019-3863.html
Created libssh tracking bugs for this issue: Affects: fedora-all [bug 1690246] Created mingw-libssh2 tracking bugs for this issue: Affects: fedora-all [bug 1690247]
Created mingw-libssh2 tracking bugs for this issue: Affects: epel-7 [bug 1690248]
Created libssh2 tracking bugs for this issue: Affects: fedora-all [bug 1690408]
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2019:0679 https://access.redhat.com/errata/RHSA-2019:0679
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2019:1175 https://access.redhat.com/errata/RHSA-2019:1175
This issue has been addressed in the following products: Red Hat Enterprise Linux 6 Via RHSA-2019:1652 https://access.redhat.com/errata/RHSA-2019:1652
This issue has been addressed in the following products: Red Hat Enterprise Linux 7.5 Extended Update Support Via RHSA-2019:1791 https://access.redhat.com/errata/RHSA-2019:1791
This issue has been addressed in the following products: Red Hat Enterprise Linux 7.4 Extended Update Support Via RHSA-2019:1943 https://access.redhat.com/errata/RHSA-2019:1943
This issue has been addressed in the following products: Red Hat Enterprise Linux 7.3 Advanced Update Support Red Hat Enterprise Linux 7.3 Update Services for SAP Solutions Red Hat Enterprise Linux 7.3 Telco Extended Update Support Via RHSA-2019:2399 https://access.redhat.com/errata/RHSA-2019:2399
> Doc Text: A flaw was found in libssh. Please note libssh & libssh2 are completely separate and unrelated libraries. In this case the flaw applies only to libssh2.