Bug 1383966 (CVE-2016-8605)

Summary:	CVE-2016-8605 guile: Thread-unsafe umask modification
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dmoppert, jskarvad, jsynacek, mlichvar, slawomir
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	guile 2.0.13	Doc Type:	If docs needed, set a value
Doc Text:	A vulnerability was found in guile, in the mkdir procedure's usage of umask(2). Under particular circumstances, an attacker could influence an application written in guile to create directories or files insecurely, potentially exposing them to being read or manipulated by local users.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-12-16 05:05:22 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:	1383973, 1383974, 1383975
Bug Blocks:	1383977

Description Andrej Nemec 2016-10-12 09:23:17 UTC

The mkdir procedure of GNU Guile, an implementation of the Scheme programming language, temporarily changed the process' umask to zero. During that time window, in a multithreaded application, other threads could end up creating files with insecure permissions. For example, mkdir without the optional mode argument would create directories as 0777.

Upstream bug:

http://debbugs.gnu.org/cgi/bugreport.cgi?bug=24659

Upstream patch:

http://git.savannah.gnu.org/cgit/guile.git/commit/?h=stable-2.0&id=245608911698adb3472803856019bdd5670b6614

References:

http://seclists.org/oss-sec/2016/q4/92

Comment 1 Andrej Nemec 2016-10-12 09:33:08 UTC

Created compat-guile18 tracking bugs for this issue:

Affects: fedora-all [bug 1383974]
Affects: epel-7 [bug 1383975]

Comment 2 Andrej Nemec 2016-10-12 09:33:15 UTC

Created guile tracking bugs for this issue:

Affects: fedora-all [bug 1383973]

Comment 3 Doran Moppert 2016-12-16 04:56:46 UTC

The opportunity for impact here is quite small, requiring mkdir-with-mask to be executed simultaneously with either mkdir-without-mask or create-file-without-mask in another thread.  The impact is for a directory or file to be created with too-permissive permissions, so that another local user might be able to read or write to it - subject to permissions of its containing directory.

Comment 4 Doran Moppert 2016-12-16 05:04:57 UTC

Statement:

Red Hat Product Security has rated this issue as having Low security
impact. This issue is not currently planned to be addressed in future
updates. For additional information, refer to the Issue Severity
Classification: https://access.redhat.com/security/updates/classification/.