Bug 1383966 – CVE-2016-8605 guile: Thread-unsafe umask modification

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Bug 1383966 - (CVE-2016-8605) CVE-2016-8605 guile: Thread-unsafe umask modification

Summary:	CVE-2016-8605 guile: Thread-unsafe umask modification

Status:	CLOSED WONTFIX

Aliases:	CVE-2016-8605

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	low Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=low,public=20161010,reported=2...
Keywords:	Security

Depends On:	1383973 1383974 1383975
Blocks:	1383977
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Reported:	2016-10-12 05:23 EDT by Andrej Nemec
Modified:	2016-12-16 09:28 EST (History)
CC List:	5 users (show)

See Also:
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:	---
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Environment:
Last Closed:	2016-12-16 00:05:22 EST
Type:	---
Regression:	---
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Documentation:	---
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oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
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Description Andrej Nemec 2016-10-12 05:23:17 EDT

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 05:33:08 EDT

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 05:33:15 EDT

Created guile tracking bugs for this issue:

Affects: fedora-all [bug 1383973]

Comment 3 Doran Moppert 2016-12-15 23:56:46 EST

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 00:04:57 EST

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/.

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