Bug 1360339 – CVE-2016-6293 icu: Out-of-bounds access in uloc_acceptLanguageFromHTTP

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Bug 1360339 - (CVE-2016-6293) CVE-2016-6293 icu: Out-of-bounds access in uloc_acceptLanguageFromHTTP

Summary:	CVE-2016-6293 icu: Out-of-bounds access in uloc_acceptLanguageFromHTTP

Status:	CLOSED WONTFIX

Aliases:	CVE-2016-6293

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
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URL:
Whiteboard:	impact=low,public=20160703,reported=2...
Keywords:	Security

Depends On:	1360341 1360342 1360340
Blocks:	1360344
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Reported:	2016-07-26 08:47 EDT by Adam Mariš
Modified:	2016-11-29 22:50 EST (History)
CC List:	19 users (show)

See Also:
Fixed In Version:	icu 58.1
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Last Closed:	2016-11-29 22:50:06 EST
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Description Adam Mariš 2016-07-26 08:47:47 EDT

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 08:50:09 EDT

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 08:50:20 EDT

Created icu tracking bugs for this issue:

Affects: fedora-all [bug 1360340]

Comment 3 Eike Rathke 2016-07-26 09:21:02 EDT

And the patch fixing this is ... where?

Comment 4 Eike Rathke 2016-08-26 05:20:21 EDT

Any update on this?

Comment 5 Michael K Johnson (@SAS) 2016-08-29 09:50:27 EDT

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 2016-09-27 22:40:31 EDT

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 2016-09-28 23:56:41 EDT

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 04:36:38 EDT

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

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

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