CVE-2026-33603 Affecting dovecot package, versions <1:2.3.21+dfsg1-2ubuntu6.5


Severity

Recommended
0.0
medium
0
10

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.21% (12th percentile)

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  • Snyk IDSNYK-UBUNTU2404-DOVECOT-16699673
  • published2 Jun 2026
  • disclosed12 May 2026

Introduced: 12 May 2026

CVE-2026-33603  (opens in a new tab)

How to fix?

Upgrade Ubuntu:24.04 dovecot to version 1:2.3.21+dfsg1-2ubuntu6.5 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream dovecot package and not the dovecot package as distributed by Ubuntu. See How to fix? for Ubuntu:24.04 relevant fixed versions and status.

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 Base Scores

version 3.1