OpenSSL Security Advisory

bn_sqrx8x_internal carry bug on x86_64 (CVE-2017-3736)

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Severity: Moderate

There is a carry propagating bug in the x86_64 Montgomery squaring procedure. No

EC algorithms are affected. Analysis suggests that attacks against RSA and DSA

as a result of this defect would be very difficult to perform and are not

believed likely. Attacks against DH are considered just feasible (although very

difficult) because most of the work necessary to deduce information

about a private key may be performed offline. The amount of resources

required for such an attack would be very significant and likely only

accessible to a limited number of attackers. An attacker would

additionally need online access to an unpatched system using the target

private key in a scenario with persistent DH parameters and a private

key that is shared between multiple clients.

This only affects processors that support the BMI1, BMI2 and ADX extensions like

Intel Broadwell (5th generation) and later or AMD Ryzen.

Note: This issue is very similar to CVE-2017-3732 and CVE-2015-3193 but must be

treated as a separate problem.

OpenSSL 1.1.0 users should upgrade to 1.1.0g

OpenSSL 1.0.2 users should upgrade to 1.0.2m

This issue was reported to OpenSSL on 10th August 2017 by the OSS-Fuzz project.

The fix was developed by Andy Polyakov of the OpenSSL development team.

Malformed X.509 IPAddressFamily could cause OOB read (CVE-2017-3735)

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Severity: Low

This issue was previously announced in security advisory

https://www.openssl.org/news/secadv/20170828.txt, but the fix has not previously

been included in a release due to its low severity.

OpenSSL 1.1.0 users should upgrade to 1.1.0g

OpenSSL 1.0.2 users should upgrade to 1.0.2m

Note

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Support for version 1.0.1 ended on 31st December 2016. Support for versions

0.9.8 and 1.0.0 ended on 31st December 2015. Those versions are no longer

receiving security updates.

References

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URL for this Security Advisory:

https://www.openssl.org/news/secadv/20171102.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