Vulnerability · CVE-2025-59028
When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail.
Published Mar 27, 2026 · corrected/updated Oct 7, 2026 · dovecot dovecot · evidence confidence high
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.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2025-59028 is a high public vulnerability record for dovecot dovecot. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether dovecot dovecot is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: dovecot/dovecot; open-xchange/dovecot. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 7.5 (technical impact); EPSS 0.4% (30-day exploitation probability). It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-20. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Mar 27, 2026 · NIST NVD
Detected
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.
Oct 7, 2026 · NIST NVD
Updated
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.
Affected
- cpe dovecot/dovecotversion unspecified
- cpe open-xchange/dovecotversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2025-59028
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2025-59028
30-day exploitation probability 0.4%
first.org - NIST NVDVulnerability recordCVE-2025-59028
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 lo
nvd.nist.gov