Bug 1687305 (CVE-2019-3857) - CVE-2019-3857 libssh2: Integer overflow in SSH packet processing channel resulting in out of bounds write
Summary: CVE-2019-3857 libssh2: Integer overflow in SSH packet processing channel resu...
Status: NEW
Alias: CVE-2019-3857
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard: impact=important,public=20190313,repo...
Keywords: Security
Depends On: 1688182 1688426 1690247 1690248 1694993 1697694 1688181 1688427 1690408 1696058 1697684
Blocks: 1687317
TreeView+ depends on / blocked
 
Reported: 2019-03-11 08:55 UTC by Andrej Nemec
Modified: 2019-05-14 18:13 UTC (History)
17 users (show)

(edit)
An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 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.
Clone Of:
(edit)
Last Closed:


Attachments (Terms of Use)


External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2019:0960 None None None 2019-05-01 17:22 UTC
Red Hat Product Errata RHBA-2019:1141 None None None 2019-05-09 21:18 UTC
Red Hat Product Errata RHSA-2019:0679 None None None 2019-03-28 15:24 UTC
Red Hat Product Errata RHSA-2019:1175 None None None 2019-05-14 18:13 UTC

Description Andrej Nemec 2019-03-11 08:55:00 UTC
A server could send a SSH_MSG_CHANNEL_REQUEST packet with an exit signal message
with a length of max unsigned integer value. The length would then have a value
of 1 added to it and used to allocate memory causing a possible memory write out
of bounds error or zero byte allocation.

Comment 2 Andrej Nemec 2019-03-12 09:15:17 UTC
Acknowledgments:

Name: the libssh2 project
Upstream: Chris Coulson (Canonical Ltd.)

Comment 4 Riccardo Schirone 2019-03-13 10:37:19 UTC
Function _libssh2_packet_add() in packet.c does not properly check the namelen value of a SSH_MSG_CHANNEL_REQUEST message, with an exit signal. The value could overflow and is used to allocate memory later on.

Comment 5 Riccardo Schirone 2019-03-13 10:37:48 UTC
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).

Comment 11 Doran Moppert 2019-03-19 04:41:10 UTC
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.

Comment 13 Dhananjay Arunesh 2019-03-19 06:29:35 UTC
External References:

https://www.libssh2.org/CVE-2019-3857.html

Comment 14 Dhananjay Arunesh 2019-03-19 06:47:55 UTC
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]

Comment 15 Dhananjay Arunesh 2019-03-19 06:49:22 UTC
Created mingw-libssh2 tracking bugs for this issue:

Affects: epel-7 [bug 1690248]

Comment 16 Andrej Nemec 2019-03-19 12:28:10 UTC
Created libssh2 tracking bugs for this issue:

Affects: fedora-all [bug 1690408]

Comment 22 errata-xmlrpc 2019-03-28 15:24:19 UTC
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

Comment 26 errata-xmlrpc 2019-05-14 18:13:43 UTC
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


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