What’s Vulnerable › Vulnerabilities

CVE-2026-33603

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-99

Description

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.

Affected products

• dovecot: before 2.4.4 — fixed in 2.4.4
• Open-Xchange Dovecot: before 3.1.5 — fixed in 3.1.5

How to fix

Upgrade to a fixed version: dovecot 2.4.4; Open-Xchange Dovecot 3.1.5. Check the vendor advisory for mitigations.

References

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

Get alerted when CVE-2026-33603 or the next vulnerability affects your stack