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LIN8-3423 : Security Advisory - OpenSSL - CVE-2016-2106

Created: Apr 28, 2016    Updated: Dec 3, 2018
Resolved Date: May 12, 2016
Found In Version:
Fix Version:
Severity: Standard
Applicable for: Wind River Linux 8
Component/s: Userspace


EVP_EncryptUpdate overflow (CVE-2016-2106)

Severity: Low

An overflow can occur in the EVP_EncryptUpdate() function. If an attacker is
able to supply very large amounts of input data after a previous call to
EVP_EncryptUpdate() with a partial block then a length check can overflow
resulting in a heap corruption. Following an analysis of all OpenSSL internal
usage of the EVP_EncryptUpdate() function all usage is one of two forms.
The first form is where the EVP_EncryptUpdate() call is known to be the first
called function after an EVP_EncryptInit(), and therefore that specific call
must be safe. The second form is where the length passed to EVP_EncryptUpdate()
can be seen from the code to be some small value and therefore there is no
possibility of an overflow. Since all instances are one of these two forms, it
is believed that there can be no overflows in internal code due to this problem.
It should be noted that EVP_DecryptUpdate() can call EVP_EncryptUpdate() in
certain code paths. Also EVP_CipherUpdate() is a synonym for
EVP_EncryptUpdate(). All instances of these calls have also been analysed too
and it is believed there are no instances in internal usage where an overflow
could occur.

This could still represent a security issue for end user code that calls this
function directly.

This issue was reported to OpenSSL on 3rd March 2016 by Guido Vranken. The
fix was developed by Matt Caswell of the OpenSSL development team.

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