====================================================================

                             CERT-Renater

                 Note d'Information No. 2021/VULN181
_____________________________________________________________________

DATE                : 26/03/2021

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running OpenSSL versions 1.1.1 prior
                                     to 1.1.1k.

=====================================================================
https://www.openssl.org/news/secadv/20210325.txt
_____________________________________________________________________

OpenSSL Security Advisory [25 March 2021]
=========================================

CA certificate check bypass with X509_V_FLAG_X509_STRICT (CVE-2021-3450)
========================================================================

Severity: High

The X509_V_FLAG_X509_STRICT flag enables additional security checks of
the certificates present in a certificate chain. It is not set by
default.

Starting from OpenSSL version 1.1.1h a check to disallow certificates in
the chain that have explicitly encoded elliptic curve parameters was
added as an additional strict check.

An error in the implementation of this check meant that the result of a
previous check to confirm that certificates in the chain are valid CA
certificates was overwritten. This effectively bypasses the check
that non-CA certificates must not be able to issue other certificates.

If a "purpose" has been configured then there is a subsequent
opportunity for checks that the certificate is a valid CA.  All of the
named "purpose" values implemented in libcrypto perform this check.
Therefore, where a purpose is set the certificate chain will still be
rejected even when the strict flag has been used. A purpose is set by
default in libssl client and server certificate verification routines,
but it can be overridden or removed by an application.

In order to be affected, an application must explicitly set the
X509_V_FLAG_X509_STRICT verification flag and either not set a purpose
for the certificate verification or, in the case of TLS client or server
applications, override the default purpose.

OpenSSL versions 1.1.1h and newer are affected by this issue. Users of
these versions should upgrade to OpenSSL 1.1.1k.

OpenSSL 1.0.2 is not impacted by this issue.

This issue was reported to OpenSSL on 18th March 2021 by Benjamin Kaduk
from Akamai and was discovered by Xiang Ding and others at Akamai. The
fix was developed by Tomáš Mráz.


NULL pointer deref in signature_algorithms processing (CVE-2021-3449)
=====================================================================

Severity: High

An OpenSSL TLS server may crash if sent a maliciously crafted
renegotiation ClientHello message from a client. If a TLSv1.2
renegotiation ClientHello omits the signature_algorithms extension
(where it was present in the initial ClientHello), but includes a
signature_algorithms_cert extension then a NULL pointer dereference will
result, leading to a crash and a denial of service attack.

A server is only vulnerable if it has TLSv1.2 and renegotiation enabled
(which is the default configuration). OpenSSL TLS clients are not
impacted by this issue.

All OpenSSL 1.1.1 versions are affected by this issue. Users of these
versions should upgrade to OpenSSL 1.1.1k.

OpenSSL 1.0.2 is not impacted by this issue.

This issue was reported to OpenSSL on 17th March 2021 by Nokia. The fix
was developed by Peter Kästle and Samuel Sapalski from Nokia.

Note
====

OpenSSL 1.0.2 is out of support and no longer receiving public updates.
Extended support is available for premium support customers:
https://www.openssl.org/support/contracts.html

OpenSSL 1.1.0 is out of support and no longer receiving updates of any
kind. The impact of these issues on OpenSSL 1.1.0 has not been analysed.

Users of these versions should upgrade to OpenSSL 1.1.1.

References
==========

URL for this Security Advisory:
https://www.openssl.org/news/secadv/20210325.txt

Note: the online version of the advisory may be updated with additional
details over time.

For details of OpenSSL severity classifications please see:
https://www.openssl.org/policies/secpolicy.html


=========================================================
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