CVE-2026-33604
Last modified
CVE-2026-33604 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. An attacker that can get Dovecot to relay a message, for example through Sieve redirect or submission relay, can use a crafted line ending in the message body to bypass the outbound protection that prevents message content from being interpreted as SMTP commands. A downstream mail server that hasn't yet fixed the SMTP smuggling vulnerability can be tricked into treating part of the message body as new SMTP commands, allowing injection of spoofed email. EPSS estimates a 0.27% chance of exploitation in the next 30 days.
Description
An attacker that can get Dovecot to relay a message, for example through Sieve redirect or submission relay, can use a crafted line ending in the message body to bypass the outbound protection that prevents message content from being interpreted as SMTP commands. A downstream mail server that hasn't yet fixed the SMTP smuggling vulnerability can be tricked into treating part of the message body as new SMTP commands, allowing injection of spoofed email. This is the same vulnerability class as CVE-2023-51764 and CVE-2023-51766. Where you control the receiving mail servers, ensure they reject bare carriage returns in message data. Update to non-vulnerable version. No publicly available exploits are known.
Metrics
Weakness Enumeration
Affected Software
Source: CNA advisory (CVE.org). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro | >= 2.3.0, < 2.3.22.2; >= 3.0.0, < 3.0.7; >= 3.1.0, < 3.1.6 |
| Open-Xchange GmbH | OX Dovecot CE | >= 2.3.0, < 2.4.5 |
References
Timeline
- Published
- Last Modified
- Status
- Deferred
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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