CVE-2026-75805
Description
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).
Statement
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.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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