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OpenSSL DTLS Retransmission Use-After-Free Denial of Service
CVE-2013-6450 affects OpenSSL 1.0.0 before 1.0.0l and 1.0.1 before 1.0.1f. The DTLS implementation improperly maintains encryption and digest contexts during renegotiation and handshake retransmission. When a renegotiation handshake packet is lost or discarded, retransmission can attempt to use a freed cryptographic context, potentially crashing the application. A man-in-the-middle attacker can trigger this condition by interfering with packet delivery. Both DTLS clients and servers are affected. OpenSSL 0.9.8 does not have the security impact because its corresponding behavior does not access a freed context.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can crash an application using the affected OpenSSL DTLS implementation, disrupting client or server availability. Packet loss during DTLS renegotiation can also trigger the crash without malicious interference. Arbitrary code execution and sensitive-data disclosure are not established for this vulnerability.
If you can’t patch tonight, do this now.
Until patching is possible, limit network exposure of affected services and disable unnecessary services using the vulnerable library. These measures reduce exposure but do not correct the context-management defect; no complete workaround is identified.
Patch, then assume compromise.
Install a vendor-supported OpenSSL update containing the complete fix. Historical upstream fixes were released in OpenSSL 1.0.0l and 1.0.1f; these branches are now unsupported. Vendor-backported fixes include Red Hat Enterprise Linux 6 package release 1.0.1e-16.el6_5.4 under RHSA-2014:0015 and Debian wheezy release 1.0.1e-2+deb7u1. Ensure backports include the additional required correction, because incomplete patching caused further crashes in some deployments. Restart all services linked to OpenSSL, or reboot, after updating.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
18 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.