Bug 1360339 (CVE-2016-6293)

Summary:	CVE-2016-6293 icu: Out-of-bounds access in uloc_acceptLanguageFromHTTP
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	abhgupta, caolanm, denis.arnaud_fedora, dmcphers, dmoppert, erack, erik-fedora, jialiu, jokerman, kseifried, lmeyer, mfabian, Michael.Johnson, mmccomas, rmeggins, sardella, slawomir, tiwillia, tuxator
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	icu 58.1	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-11-30 03:50:06 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:	1360340, 1360341, 1360342
Bug Blocks:	1360344

Description Adam Mariš 2016-07-26 12:47:47 UTC

It was found that uloc_acceptLanguageFromHTTP function in common/uloc.cpp does not ensure that there is a '\0' character at the end of a certain temporary array that leads to out of bounds access, possibly causing DoS.

CVE assignment:

http://seclists.org/oss-sec/2016/q3/137

Comment 1 Adam Mariš 2016-07-26 12:50:09 UTC

Created mingw-icu tracking bugs for this issue:

Affects: fedora-all [bug 1360341]
Affects: epel-7 [bug 1360342]

Comment 2 Adam Mariš 2016-07-26 12:50:20 UTC

Created icu tracking bugs for this issue:

Affects: fedora-all [bug 1360340]

Comment 3 Eike Rathke 2016-07-26 13:21:02 UTC

And the patch fixing this is ... where?

Comment 4 Eike Rathke 2016-08-26 09:20:21 UTC

Any update on this?

Comment 5 Michael K Johnson (@SAS) 2016-08-29 13:50:27 UTC

I don't even find a bug filed in the icu bug tracker upstream:
http://bugs.icu-project.org/trac/search?q=CVE-2016-6293
However, at https://sourceforge.net/p/icu/mailman/message/35305922/
upstream say they "are tracking this issue"

Maybe they have a private ticket in trac for a publicly-disclosed
vulnerability?

Comment 6 Doran Moppert 2016-09-28 02:40:31 UTC

It looks like the patch is http://bugs.icu-project.org/trac/changeset/39109 - referenced ticket is private but description, timeline and tests look correct.

Comment 7 Doran Moppert 2016-09-29 03:56:41 UTC

Impact here looks relatively low:

 - a string of the precise length fails to be null terminated, causing out-of-bounds read in strcmp().  At worst this is a crash.

 - other than php, no packages shipped in Red Hat Enterprise Linux use this function


Third-party code can protect itself in the same way as PHP, by ensuring the httpAcceptLanguage parameter passed to uloc_acceptLanguageFromHTTP is no longer than ULOC_FULLNAME_CAPACITY bytes.  This constant is defined as 157 in libicu-50.1.2, which is more than enough for a legitimate Accept-Language string.

libicu does not make any internal calls to uloc_acceptLanguageFromHTTP, so a simple grep for that entry point is sufficient to determine if client code is vulnerable.

Comment 9 Doran Moppert 2016-11-04 08:36:38 UTC

Upstream bug (ICU) (private as at 2016-11-04):

http://bugs.icu-project.org/trac/ticket/12652