Hash: SHA256

             AUSCERT External Security Bulletin Redistribution

                          OpenSSL security update
                               26 March 2021


        AusCERT Security Bulletin Summary

Product:           OpenSSL
Publisher:         OpenSSL
Operating System:  UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Denial of Service              -- Unknown/Unspecified
                   Access Confidential Data       -- Unknown/Unspecified
                   Provide Misleading Information -- Unknown/Unspecified
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-3450 CVE-2021-3449 

Original Bulletin: 

Comment: This advisory references vulnerabilities in OpenSSL products which run on 
         multiple platforms. It is recommended that administrators
         running OpenSSL check for an updated version of the software for 
         their operating system.

- --------------------------BEGIN INCLUDED TEXT--------------------

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

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

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.


OpenSSL 1.0.2 is out of support and no longer receiving public updates. Extended
support is available for premium support customers:

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.


URL for this Security Advisory:

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

For details of OpenSSL severity classifications please see:

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:


Australian Computer Emergency Response Team
The University of Queensland
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
Comment: http://www.auscert.org.au/render.html?it=1967