Bug 1218426

Summary:	gnutls: MD5-based ServerKeyExchange signature accepted by default (GNUTLS-SA-2015-2)
Product:	[Other] Security Response	Reporter:	Fabio Olive Leite <fleite>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	carnil, fweimer
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-06-12 03:03:54 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:	1218513
Bug Blocks:	1218474

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.