Bug 1411794 (CVE-2016-10127)

Summary:	CVE-2016-10127 python-pysaml2: Vulnerable to XML external entity attack
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aortega, apevec, apevec, ayoung, chrisw, cvsbot-xmlrpc, dmoppert, jdennis, jjoyce, jschluet, kbasil, lhh, lpeer, markmc, nkinder, rbryant, rcritten, rhos-maint, sardella, sclewis, slong, tdecacqu
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-03-30 03:59:19 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:	1395609
Bug Blocks:	1411796

Description Andrej Nemec 2017-01-10 13:54:52 UTC

It was found that python-pysaml2 is vulnerable to an XML external entity attack. python-pysaml2 does not sanitize SAML XML requests or responses.

References:

http://seclists.org/oss-sec/2017/q1/50
https://bugs.debian.org/850716

Upstream bug:

https://github.com/rohe/pysaml2/issues/366

Proposed patch (! actually fixes Bug 1415710):

https://github.com/rohe/pysaml2/pull/379

Comment 1 Andrej Nemec 2017-01-11 09:08:43 UTC

CVE assignment:

http://seclists.org/oss-sec/2017/q1/58

Comment 10 Lon Hohberger 2017-01-24 18:32:32 UTC

John, one note for OpenStack builds:

https://github.com/openstack/requirements/blob/master/global-requirements.txt#L210

If you rebase to a version > 4.0.2, you *must* also merge this patch:

https://github.com/rohe/pysaml2/pull/385

Comment 11 Lon Hohberger 2017-01-24 18:37:38 UTC

Note that the proposed patch requires a new package, python-defusedxml, to be added on releases which did not previously include it.

Comment 12 Doran Moppert 2017-01-25 00:53:51 UTC

(In reply to Lon Hohberger from comment #11)
> Note that the proposed patch requires a new package, python-defusedxml, to
> be added on releases which did not previously include it.

Well spotted Lon.

It turns out this patch actually fixes the incorrect flaw.  The patch referenced in comment 0 addresses bug 1415710 (CVE-2016-10149) - there is currently no proposed fix for CVE-2016-10127.

There may be a partial fix for this flaw in passing resolve_entities=False to lxml *if* SAML can operate correctly without the use of entities.  I say "partial" because pySAML also uses xmlsec, which presently has no such mitigation.


A proper root cause fix will come from bug 1395609 (libxml2), once the patch under development there has been verified by the developers.

Comment 15 Alan Pevec 2017-03-17 12:13:34 UTC

Based on comment 12 fix for this depends on yet unresolved libxml2 bug 1395609 and previous product BZ clones were moved to block new CVE-2016-10149 for which there is a fix.

Comment 17 Summer Long 2017-03-30 04:01:30 UTC

Statement:

This flaw resides in the XML Security Library (xmlsec1) and will be updated there; Red Hat OpenStack Platform is not affected.