# CVE-2026-75805: OpenSSL CMP client NULL pointer dereference in revocation

Source: https://junglewise.ai/threats/cve-2026-75805-issue-summary-a-cmp-client-that-requests-certificate-revocation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-75805 · Severity: medium · CVSS 5.3 · Published 2026-09-29

OpenSSL's Certificate Management Protocol (CMP) client can crash when processing a specially crafted revocation response from a malicious or compromised CMP server. This occurs only when the client attempts to revoke a certificate using a PKCS#10 CSR (certificate request) instead of the certificate itself. An attacker who can intercept or control the CMP server's response can trigger a denial of service by causing the client application to crash.

Technologies: [OpenSSL](https://junglewise.ai/threats/technologies/openssl). Vendors: [OpenSSL](https://junglewise.ai/threats/vendors/openssl).

## Quick answers

**Is CVE-2026-75805 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-75805 being exploited in the wild.

**How severe is CVE-2026-75805?** Medium severity, with a CVSS score of 5.3, published 29 September 2026.

**Which products and versions are affected?** OpenSSL <UNKNOWN>.

**Is there a fix for CVE-2026-75805?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-75805 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-75805?** Check whether you run OpenSSL at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a NULL pointer dereference (CWE-476) in OpenSSL's CMP protocol implementation when handling revocation responses. When a client revokes a certificate via PKCS#10 CSR, it sends no issuer name or serial number; if the server's response includes a crafted certificate identifier, the client attempts to compare it against uninitialized NULL pointers, causing a crash. The attack requires the attacker to be a malicious CMP server or man-in-the-middle with knowledge of the message protection secret; clients using certificate or issuer/serial number identification are unaffected.

## Affected products

- OpenSSL OpenSSL <UNKNOWN>

## Timeline

- 2026-09-29: disclosed

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