Bug 1218426 - gnutls: MD5-based ServerKeyExchange signature accepted by default (GNUTLS-SA-2015-2)
Summary: gnutls: MD5-based ServerKeyExchange signature accepted by default (GNUTLS-SA-...
Keywords:
Status: CLOSED WONTFIX
Alias: None
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1218513
Blocks: 1218474
TreeView+ depends on / blocked
 
Reported: 2015-05-04 21:05 UTC by Fabio Olive Leite
Modified: 2021-06-12 03:03 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2021-06-12 03:03:54 UTC
Embargoed:

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Description Fabio Olive Leite 2015-05-04 21:05:44 UTC 
It was reported by the GnuTLS project that a ServerKeyExchange signature
sent by the server is not verified to be in the acceptable by the client
set of algorithms. That has the effect of allowing MD5 signatures (which
are disabled by default) in the ServerKeyExchange message. It is not
believed that this bug can be exploited because a fraudulent signature has
to be generated in real-time which is not known to be possible. However,
since attacks can only get better it is recommended to update to a GnuTLS
version which addresses the issue.

References:
http://www.gnutls.org/security.html
Comment 3 Florian Weimer 2015-05-05 07:13:57 UTC 
Created gnutls tracking bugs for this issue:

Affects: fedora-all [bug 1218513]
Comment 4 Florian Weimer 2015-05-05 07:14:32 UTC 
Statement:

The gnutls packages in Red Hat Enterprise Linux 5 do not support TLS 1.2 and are not affected by this flaw.

Red Hat Product Security has rated this issue as having Low security impact. For Red Hat Enterprise Linux 6 and 7, a future update may address this flaw.
Comment 6 Fedora Update System 2015-05-11 19:07:56 UTC 
gnutls-3.3.15-1.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.
Comment 7 Fedora Update System 2015-05-14 11:15:20 UTC 
gnutls-3.3.15-1.fc21 has been pushed to the Fedora 21 stable repository.  If problems still persist, please make note of it in this bug report.
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