CVE-2025-59028

Medium

Description

When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail. Invalid BASE64 data can be used to DoS a vulnerable server to break concurrent logins. Install fixed version or disable concurrency in login processes (heavy perfomance penalty on large deployments). No publicly available exploits are known.

SeverityMedium

CVSS5.3

Exploit probability—

ProductDovecot

PublishedMar 27, 2026

First seenMar 27, 2026

Weakness typeCWE-20Improper input validation

How to fix

Update

dovecot dovecot2.4.3 or later
open-xchange dovecot3.1.2 or later

Vendor advisories

documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json

Affected products

Product	Affected versions	Fixed in
dovecot dovecot	v < 2.4.3	2.4.3
open-xchange dovecot	v < 3.1.2	3.1.2

Check your version

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