Opened 7 years ago

Closed 7 years ago

#6463 closed enhancement (fixed)


Reported by: Fernando de Oliveira Owned by: Fernando de Oliveira
Priority: normal Milestone: 7.8
Component: BOOK Version: SVN
Severity: normal Keywords:


Severity: ServerKeyExchange signature issue

Karthikeyan Bhargavan reported 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.

Recommendation: Upgrade to GnuTLS 3.4.1, or 3.3.15

* Version 3.4.1 (released 2015-05-03)

** libgnutls: gnutls_certificate_get_ours: will return the certificate even
if a callback was used to send it.

** libgnutls: Check for invalid length in the X.509 version field. Without
the check certificates with invalid length would be detected as having an
arbitrary version. Reported by Hanno Böck.

** libgnutls: Handle DNS name constraints with a leading dot. Patch by
Fotis Loukos.

** libgnutls: Updated system-keys support for windows to compile in more
versions of mingw. Patch by Tim Kosse.

** libgnutls: Fix for MD5 downgrade in TLS 1.2 signatures. Reported by
Karthikeyan Bhargavan [GNUTLS-SA-2015-2].

** libgnutls: Reverted: The gnutls_handshake() process will enforce a timeout
by default. That caused issues with non-blocking programs.

** certtool: It can generate SHA256 key IDs.

** gnutls-cli: fixed crash in --benchmark-ciphers. Reported by James Cloos.

** configure: re-enabled the --enable-local-libopts flag

** API and ABI modifications:
gnutls_x509_crt_get_pk_ecc_raw: Added

Change History (2)

comment:1 by Fernando de Oliveira, 7 years ago

Owner: changed from blfs-book@… to Fernando de Oliveira
Status: newassigned

comment:2 by Fernando de Oliveira, 7 years ago

Resolution: fixed
Status: assignedclosed

Fixed at r15929.

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