---
cve: "CVE-2026-75805"
severity: "MEDIUM"
cvss: 5.3
epss: "0.2%"
vendor: "OpenSSL"
kev: false
exploited: false
published: "2026-09-29 15:32:20"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-10-02T10:32:34+02:00"
---

# CVE-2026-75805

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

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 ' 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.

## CNA-Record (Kanon, cvelistV5)

- CNA: **openssl**
- State: PUBLISHED
- Stand: 2026-09-29 16:54:39

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Gering | warn |

## Schwachstellen-Klasse

- **CWE-476** — NULL Pointer Dereference
  The product dereferences a pointer that it expects to be valid but is NULL.

## Patch verfügbar (OSV)

- af1775b60dfa141a4ad762585052cabeb9f37e9e (Commit)
- c8bd5a57108599ac650bbae77fcabe3109dab2e8 (Commit)

## BSI-Hinweise (deutsch)

- [OpenSSL: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-3638) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in OpenSSL ausnutzen, um Sicherheitsvorkehrungen zu umgehen, vertrauliche Informationen offenzulegen, Daten zu manipulieren und einen Denial-of-Service-Zustand zu verursachen.

## Referenzen

- <https://openssl-library.org/news/secadv/20260929.txt>
- <https://github.com/openssl/openssl/commit/7ca0ccb5172a577e9b87267d77bfe21e5481a5e7>
- <https://github.com/openssl/openssl/commit/7588db7fef14209c3caa3a101d11a02006b19166>
- <https://github.com/openssl/openssl/commit/9eb2a8a9b86136cdb39d6d7d50644dd66941cdc3>
- <https://github.com/openssl/openssl/commit/abf02872a4b71767ecc72293424420f5b009190f>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-75805) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_