CVE-2026-42765

A flaw was found in OpenSSL. When an application is configured with specific non-default settings for certificate verification, including both Online Certificate Status Protocol (OCSP) response checking and partial chain verification, a NULL dereference can occur. This vulnerability can be triggered if the certificate chain lacks a self-signed trusted anchor, causing the application to crash. This leads to a Denial of Service (DoS) for the affected application.

This issue is rated as Low impact. A NULL pointer dereference can occur in applications that enable both OCSP response checking for the entire certificate chain and partial chain verification. Since both of these flags are disabled by default in Red Hat products, the risk of exploitation is significantly reduced. This flaw could lead to a Denial of Service if an application is configured with these non-default settings.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, ensure that applications do not enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial chain verification (X509_V_FLAG_PARTIAL_CHAIN) simultaneously. These flags are disabled by default, and maintaining the default configuration prevents exposure to this flaw. Consult application-specific documentation for details on how to configure certificate verification flags.