CVE-2026-28388

Name of the Vulnerable Software and Affected Versions OpenSSL versions 3.0 through 3.6

Description A NULL pointer dereference can occur during the processing of a delta CRL containing a Delta CRL Indicator extension if the required CRL Number extension is missing. This can lead to a denial of service. Exploitation requires the X509 V FLAG USE DELTAS flag to be enabled, the certificate being verified to contain a freshestCRL extension or the base CRL to have the EXFLAG FRESHEST flag set, and an attacker providing a malformed CRL. The issue is limited to denial of service and cannot be escalated to code execution or memory disclosure.

Recommendations OpenSSL versions 3.0 through 3.6: Update to a newer version that contains a fix for this vulnerability.