The OpenSSL project team has released OpenSSL Version 1.1.0c that addresses three critical security vulnerabilities.
The most severe flaw which is ranked “High” is the heap-based buffer overflow bug(CVE-2016-7054) that can lead to Dos attack by corrupting larger payloads, resulting in a crash of OpenSSL, as reported by OpenSSL Team.
"TLS connections using *-CHACHA20-POLY1305 ciphersuites are susceptible to a DoS attack by corrupting larger payloads. This can result in an OpenSSL crash. This issue is not considered to be exploitable beyond a DoS."
However OpenSSL team claims that there is no evidence that this flaw is exploitable beyond Dos attack.
The second most critical vulnerability which is rated as “Moderate” severity (CVE-2016-7053), can cause the applications to crash, has also been addressed in OpenSSL 1.1.0c version release. The team explains:
"Applications parsing invalid CMS structures can crash with a NULL pointer dereference. This is caused by a bug in the handling of the ASN.1 CHOICE type in OpenSSL 1.1.0 which can result in a NULL value being passed to the structure callback if an attempt is made to free certain invalid encodings. Only CHOICE structures using a callback which do not handle NULL value are affected."
Both High & Moderate vulnerabilities only affects OpenSSL 1.1.0.
The third vulnerability addressed in OpenSSL-1.1.0c is a low severity flaw (CVE-2016-7055) which is related to Broadwell-specific Montgomery multiplication procedure that handles input lengths divisible by, butlonger than 256 bits.
This issue doesn’t affect OpenSSL versions prior to 1.0.2. Due to the low severity of this defect team has not yet issued a new 1.0.2 release & suggests the users to wait for next 1.0.2 release which should address this flaw.
All the users are strongly recommended to patch these vulnerabilities by upgrading from OpenSSL-1.1.0 version to OpenSSL-1.1.0c.