Bug 1056338 (CVE-2014-1624)

Summary:	CVE-2014-1624 pyxdg: TOCTOU race condition in get_runtime_dir() when strict=False
Product:	[Other] Security Response	Reporter:	Vincent Danen <vdanen>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED CURRENTRELEASE	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	jkurik, jpmahowald, jrusnack, pfrields, sindrepb, tcallawa, vkaigoro
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-06-01 18:06:54 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Bug Depends On:	1056339, 1056340
Bug Blocks:	1225862

Description Vincent Danen 2014-01-22 02:05:14 UTC

It was reported [1],[2] that the Python XDG module (pyxdg) suffered from a TOCTOU race condition when the xdg.BaseDirectory.get_runtime_dir() function is called with the strict setting set to False (the default is True).  When the strict setting is set to True, the directory pointed to by the $XDG_RUNTIME_DIR is used (and returned).  However, if $XDG_RUNTIME_DIR is unset, it will attempt to use the /tmp/pyxdg-runtime-dir-fallback-[username] directory.  A local attacker could use this to conduct symbolic link attacks, possibly leading to their ability to modify permissions or security context of a path different than that originally intended or requested.

This flaw only affects pyxdg 0.25 as the ability to use the $XDG_RUNTIME_DIR (and thus the introduction of this function) was first introduced there based on this Debian request [3].

No patch is yet available and discussion on the fix is taking place in the upstream bug tracker [4]. UPDATE: A Patch is available via [5]

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=736247
[2] http://www.openwall.com/lists/oss-security/2014/01/21/3
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=656338
[4] https://bugs.freedesktop.org/show_bug.cgi?id=73878
[5] https://github.com/takluyver/pyxdg/commit/bd999c1c3fe7ee5f30ede2cf704cf03e400347b4

Comment 2 Vincent Danen 2014-01-22 02:06:09 UTC

Created pyxdg tracking bugs for this issue:

Affects: fedora-all [bug 1056339]

Comment 3 Fedora Update System 2014-12-20 00:17:55 UTC

pyxdg-0.25-5.el7 has been pushed to the Fedora EPEL 7 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 4 Fedora Update System 2014-12-20 08:35:18 UTC

pyxdg-0.25-5.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 5 Fedora Update System 2014-12-25 05:35:25 UTC

pyxdg-0.25-5.fc19 has been pushed to the Fedora 19 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 6 Fedora Update System 2015-01-03 19:09:11 UTC

pyxdg-0.25-5.fc20 has been pushed to the Fedora 20 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 8 Stefan Cornelius 2015-06-01 18:06:54 UTC

This should be fixed in all current releases.