CVE-2026-75805

A flaw was found in OpenSSL. When a Certificate Management Protocol (CMP) client requests certificate revocation using a PKCS#10 Certificate Signing Request (CSR), it omits the certificate issuer name and serial number. A malicious or compromised CMP server, or an attacker possessing valid message protection credentials, can exploit this flaw by returning a crafted revocation response. This triggers a NULL pointer dereference when the client attempts to compare response data, causing the client application to crash and resulting in a Denial of Service (DoS).

This flaw is rated Moderate. It is a Denial of Service only: a CMP client can crash when processing a crafted certificate revocation response after requesting revocation with a PKCS#10 CSR. Exploitation requires a malicious or compromised CMP server, or a man-in-the-middle that already has the CMP message-protection secret. There is no confidentiality or integrity impact, FIPS modules are not affected, and clients that identify the certificate by certificate or by issuer and serial number are not affected.

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.

Do not revoke certificates over CMP by supplying a PKCS#10 CSR (openssl cmp -cmd rr -csr ... or OSSL_CMP_CTX_set1_p10CSR()). Identify the certificate by certificate or by issuer name and serial number instead. Restrict CMP clients to trusted CMP servers and protect CMP message-protection credentials. If CMP certificate revocation is unused, avoid enabling CMP client revocation workflows.