---
cve: "CVE-2026-33603"
severity: "MEDIUM"
cvss: 6.8
epss: "22%"
vendor: "Open-Xchange GmbH"
kev: false
exploited: false
published: "2026-05-12 14:17:01"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-03T04:55:29+02:00"
---

# CVE-2026-33603

> 6.8 MEDIUM

## Beschreibung

Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 8b687aa65c719e2a0d773eccea84f67c5770fc9a (Commit)

## Referenzen

- <https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.json>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-33603) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_