CVE-2016-2181: Input Validation
A flaw was found in the Datagram TLS (DTLS) replay protection implementation in OpenSSL. A remote attacker could possibly use this flaw to make a DTLS server using OpenSSL to reject further packets sent from a DTLS client over an established DTLS connection.
Other sources
It was found that when doing handshake/renegotiation, it's possible to bypass DTLS replay protection by sending a record for the next epoch (which does not have to decrypt or have a valid MAC), with a very large sequence number. This means the right hand edge of the window is moved very far to the right, and all subsequent legitimate packets are dropped causing a denial of service.
Upstream patches:
https://github.com/openssl/openssl/commit/5802758eb480c5f14a768f6a061df1dd20aec8c4 https://github.com/openssl/openssl/commit/b77ab018b79a00f789b0fb85596b446b08be4c9d https://github.com/openssl/openssl/commit/fa75569758298e2930c78989b516cac937118acc
— Red Hat
The Anti-Replay feature in the DTLS implementation in OpenSSL before 1 ...
— Debian
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2016-2181?
CVE-2016-2181 has been classified as a moderate severity vulnerability.
How do I fix CVE-2016-2181?
To fix CVE-2016-2181, you should upgrade OpenSSL to a version that addresses this vulnerability, such as 1.0.1, 1.0.2, or any later versions.
Which versions of OpenSSL are affected by CVE-2016-2181?
CVE-2016-2181 affects OpenSSL versions prior to 1.0.2 and specifically versions such as 1.0.1e and earlier.
Can CVE-2016-2181 be exploited remotely?
Yes, CVE-2016-2181 can be exploited by a remote attacker to disrupt client-server communications.
What impact does CVE-2016-2181 have on system security?
CVE-2016-2181 can lead to denial of service by causing the DTLS server to reject packets from clients, disrupting established connections.