Bug 1287572 (CVE-2015-8313)

Summary: CVE-2015-8313 gnutls: First byte of the padding in CBC mode is not checked
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: nmavrogi, tmraz
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Last Closed: 2015-12-02 12:56:26 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Blocks: 1287573    
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Patch extracted from Debian packages gnutls26-2.12.20-8+deb7u4 none

Description Adam Mariš 2015-12-02 11:23:09 UTC 
It was discovered that gnutls incorrectly validates the first byte of padding in CBC modes. A remote attacker can possibly take advantage of this flaw to perform a padding oracle attack. Affected are older versions of gnutls (2.x).

Public via:

https://www.debian.org/security/2015/dsa-3408
http://seclists.org/bugtraq/2015/Dec/0
Comment 1 Nikos Mavrogiannopoulos 2015-12-02 12:02:27 UTC 
This bug does not affect RHEL-6 or RHEL-7. They have been patched with the proper fixes for Lucky13 which included the fix for that issue.
Comment 2 Nikos Mavrogiannopoulos 2015-12-02 12:04:21 UTC 
It doesn't affect RHEL-5 either.
Comment 3 Tomas Hoger 2015-12-02 12:49:59 UTC 
Details of this issue can be found in the Hanno Böck's blog post:

https://blog.hboeck.de/archives/877-A-little-POODLE-left-in-GnuTLS-old-versions.html

Here is also the original Ubuntu bug report:

https://bugs.launchpad.net/ubuntu/+source/gnutls26/+bug/1510163
Comment 4 Tomas Hoger 2015-12-02 12:53:10 UTC 
Created attachment 1101466 [details]
Patch extracted from Debian packages gnutls26-2.12.20-8+deb7u4
Comment 5 Tomas Hoger 2015-12-02 12:56:26 UTC 
The GnuTLS version of Lucky13 got CVE-2013-1619 (bug 908238) and got corrected in Red Hat Enterprise Linux 5 and 6.  As noted above, the fix used addressed Lucky13 without leaving this small problem in.