CVE-2016-6302: Input Validation
An integer underflow flaw leading to a buffer over-read was found in the way OpenSSL parsed TLS session tickets. A remote attacker could use this flaw to crash a TLS server using OpenSSL if it used SHA-512 as HMAC for session tickets.
Other sources
It was found that if a ticket callback changes the HMAC digest to SHA512 the existing sanity checks are not sufficient and an attacker could perform a DoS attack with a malformed ticket.
Upstream patch:
https://github.com/openssl/openssl/commit/1bbe48ab149893a78bf99c8eb8895c928900a16f
— Red Hat
The tlsdecryptticket function in ssl/t1lib.c in OpenSSL before 1.1.0 does not consider the HMAC size during validation of the ticket length, which allows remote attackers to cause a denial of service via a ticket that is too short.
Affected Software
Remediation
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2016-6302?
CVE-2016-6302 is considered a critical severity vulnerability due to its potential to crash TLS servers.
How do I fix CVE-2016-6302?
To fix CVE-2016-6302, you should upgrade to the latest versions of the affected software packages listed in the vulnerability details.
What causes CVE-2016-6302?
CVE-2016-6302 is caused by an integer underflow flaw in OpenSSL when parsing TLS session tickets.
Is CVE-2016-6302 exploitable over the network?
Yes, CVE-2016-6302 can be exploited remotely, allowing attackers to crash servers using vulnerable versions of OpenSSL.
What versions of OpenSSL are affected by CVE-2016-6302?
CVE-2016-6302 affects various versions of OpenSSL, particularly those prior to the patched versions that address this vulnerability.