---
id: CVE-2026-75805
title: |-
  Issue summary: A CMP client that requests certificate revocation on the basis
  of a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when
  processing a crafted revocation response
summary: |-
  Issue summary: A CMP client that requests certificate revocation on the basis
  of a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when
  processing a crafted revocation response. 

  Impact summary: The NULL pointer dere…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-476
vendor: OpenSSL
product: OpenSSL
affected:
  - OpenSSL >= 4.0.0 < 4.0.3
  - OpenSSL >= 3.6.0 < 3.6.5
  - OpenSSL >= 3.5.0 < 3.5.9
  - OpenSSL >= 3.4.0 < 3.4.8
  - OpenSSL >= 3.0.0 < 3.0.23
published: '2026-09-29'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T17:17:09.620'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-75805'
references:
  - url: >-
      https://github.com/openssl/openssl/commit/7588db7fef14209c3caa3a101d11a02006b19166
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/7ca0ccb5172a577e9b87267d77bfe21e5481a5e7
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/9eb2a8a9b86136cdb39d6d7d50644dd66941cdc3
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/abf02872a4b71767ecc72293424420f5b009190f
    label: openssl-security@openssl.org
  - url: 'https://openssl-library.org/news/secadv/20260929.txt'
    label: openssl-security@openssl.org
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-29T16:54:03.315064Z'
ingestedAt: '2026-09-29T16:39:33.267Z'
---

## Overview

Issue summary: A CMP client that requests certificate revocation on the basis
of a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when
processing a crafted revocation response. 

Impact summary: The NULL pointer dereference happens on a read which 
leads to a crash and a Denial of Service for the affected client application.

CWE: CWE-476: NULL-pointer dereference

Description: A CMP client revoking a certificate has to tell the server which
certificate to revoke, and may do so by supplying a PKCS#10 CSR instead of the
certificate itself or its issuer name and serial number. This is
'openssl cmp -cmd rr -csr <file>' on the command line, or
OSSL_CMP_exec_RR_ses() with the certificate supplied via
OSSL_CMP_CTX_set1_p10CSR() through the API.

A CSR does not contain the issuer name and serial number of the certificate,
so the client does not send them. A server may optionally name the
certificate it revoked in its response, and the client then compares that
name against what it sent. Having sent neither an issuer name nor a serial
number, it has nothing to compare against, and a server returning a specially
crafted name causes the client to read from a NULL pointer and crash.

The revocation response is checked for valid message protection before
the affected code is reached, so an attacker must be a malicious or
compromised CMP server, or a man-in-the-middle in possession of the
secret used for message protection. Clients that identify the certificate
to be revoked by a certificate or by issuer and serial number rather
than by a PKCS#10 CSR are not affected.

FIPS impact: no
No FIPS modules are affected by this issue, as the CMP protocol
implementation is outside the OpenSSL FIPS module boundary.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.