Bug 1687306 (CVE-2019-3858)

Summary:	CVE-2019-3858 libssh2: Zero-byte allocation with a specially crafted SFTP packed leading to an out-of-bounds read
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bmcclain, dblechte, dfediuck, djuran, eedri, erik-fedora, kdudka, mgoldboi, michal.skrivanek, mike, paul, rjones, rschiron, sbonazzo, security-response-team, sherold, yturgema
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libssh2 1.8.1	Doc Type:	If docs needed, set a value
Doc Text:	An out of bounds read flaw was discovered in libssh2 when a specially crafted SFTP packet is received from the server. A remote attacker who compromises a SSH server may be able to cause a denial of service or read data in the client memory.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-08-06 13:22:09 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1688433, 1688434, 1688435, 1690247, 1690248, 1690408, 1696058, 1697702
Bug Blocks:	1687317

Description Andrej Nemec 2019-03-11 08:56:17 UTC

A server could send a specially crafted partial SFTP packet with a zero value
for the payload length. This zero value would be used to then allocate memory
resulting in a zero byte allocation and possible out of bounds read.

Comment 2 Andrej Nemec 2019-03-12 09:15:22 UTC

Acknowledgments:

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

Comment 4 Riccardo Schirone 2019-03-13 17:29:34 UTC

Function sftp_packet_read() in sftp.c does not check if partial_len is zero and it is vulnerable to an out-of-bounds read.

Comment 9 Dhananjay Arunesh 2019-03-19 06:31:30 UTC

Reference:
https://www.openwall.com/lists/oss-security/2019/03/18/3

Upstream Patch:
https://libssh2.org/1.8.0-CVE/CVE-2019-3858.patch

Comment 10 Dhananjay Arunesh 2019-03-19 06:31:32 UTC

External References:

https://www.libssh2.org/CVE-2019-3858.html

Comment 11 Dhananjay Arunesh 2019-03-19 06:47:17 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 12 Dhananjay Arunesh 2019-03-19 06:48:47 UTC

Created mingw-libssh2 tracking bugs for this issue:

Affects: epel-7 [bug 1690248]

Comment 13 Andrej Nemec 2019-03-19 12:28:22 UTC

Created libssh2 tracking bugs for this issue:

Affects: fedora-all [bug 1690408]

Comment 16 errata-xmlrpc 2019-08-06 12:19:34 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2019:2136 https://access.redhat.com/errata/RHSA-2019:2136

Comment 17 Product Security DevOps Team 2019-08-06 13:22:09 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2019-3858

Comment 18 Doran Moppert 2021-02-02 04:08:41 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.

libssh2 is no longer included in the virt module since Red Hat Enterprise Linux 8.1.