# CVE-2025-59028: When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active…

Source: https://junglewise.ai/threats/cve-2025-59028-when-sending-invalid-base64-sasl-data-login-process-is  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-27  
License: CC BY 4.0 with a link back

CVE-2025-59028 · Severity: medium · CVSS 5.3 · Published 2026-03-27

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.

Technologies: [Dovecot](https://junglewise.ai/threats/technologies/dovecot), [Open-Xchange Dovecot](https://junglewise.ai/threats/technologies/open-xchange-dovecot). Vendors: [Dovecot](https://junglewise.ai/threats/vendors/dovecot), [Open-Xchange](https://junglewise.ai/threats/vendors/open-xchange).

## Quick answers

**Is CVE-2025-59028 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-59028 being exploited in the wild.

**How severe is CVE-2025-59028?** Medium severity, with a CVSS score of 5.3, published 27 March 2026.

**Which products and versions are affected?** Dovecot, Open-Xchange Dovecot. The advisory does not name versions.

**Is there a fix for CVE-2025-59028?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2025-59028?** Check whether you run Dovecot or Open-Xchange Dovecot. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Dovecot
- Open-Xchange Dovecot

## Related threats

- [Dovecot ManageSieve denial of service via malformed pre-auth command](https://junglewise.ai/threats/cve-2026-33605-dovecot-managesieve-denial-of-service-via-malformed-pre-auth)
- [Open-Xchange Dovecot uncontrolled memory consumption in IMAP](https://junglewise.ai/threats/cve-2026-42006-open-xchange-dovecot-uncontrolled-memory-consumption-in-imap)
- [Open-Xchange Dovecot improper access control in IMAP SETACL](https://junglewise.ai/threats/cve-2026-40020-open-xchange-dovecot-improper-access-control-in-imap-setacl)
- [Open-Xchange Dovecot CPU limit bypass in Sieve scripts](https://junglewise.ai/threats/cve-2026-40016-open-xchange-dovecot-cpu-limit-bypass-in-sieve-scripts)
- [Open-Xchange Dovecot SCRAM TLS channel binding spoofing](https://junglewise.ai/threats/cve-2026-33603-open-xchange-dovecot-scram-tls-channel-binding-spoofing)