CVE-2024-2511 Openssl CVE debrief

Who should care

Operators and security teams running OpenSSL-backed TLS servers with TLSv1.3, especially those using non-default session ticket settings such as SSL_OP_NO_TICKET.

Technical summary

The flaw is a server-side TLSv1.3 session-cache state bug. Under certain conditions, disabling session tickets with SSL_OP_NO_TICKET can prevent the cache from flushing correctly as it grows, leading to unbounded memory consumption. The NVD record maps the issue to CWE-1325 and lists a network-accessible denial-of-service impact only.

Defensive priority

Medium

Recommended defensive actions

• Inventory TLSv1.3 servers using OpenSSL and check for SSL_OP_NO_TICKET in production configurations.
• Review whether early_data and default anti-replay protection are enabled; avoid the vulnerable configuration path described in the advisory.
• Apply the OpenSSL fix from the vendor advisory and related commits on affected deployments.
• Monitor server memory and session-cache behavior for unexpected growth after TLS configuration changes.
• Confirm that TLS clients and unaffected builds are excluded from remediation scope, but still validate server-side deployments.

Evidence notes

Source evidence includes the OpenSSL security advisory dated 2024-04-08, the CVE record, and NVD metadata. The corpus states the issue impacts certain TLSv1.3 servers using non-default SSL_OP_NO_TICKET, is not a client issue, and does not affect OpenSSL 1.0.2 or FIPS modules in 3.0/3.1/3.2. NVD lists CVSS 3.1 vector AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H with score 5.9 and marks the record Deferred.

Official resources