CVE-2025-59028
Denial of Service via Invalid Base64 in Open-Xchange SASL Authentication
Publication date: 2026-03-27
Last updated on: 2026-04-30
Assigner: Open-Xchange
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| dovecot | dovecot | to 2.4.3 (exc) |
| open-xchange | dovecot | to 3.1.2 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-20 | The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability occurs when invalid base64 SASL data is sent during the login process, causing the authentication server to disconnect the login attempt. This disconnection results in all active authentication sessions failing.
An attacker can exploit this by sending invalid BASE64 data to perform a denial-of-service (DoS) attack on a vulnerable server, effectively breaking concurrent logins.
How can this vulnerability impact me? :
The main impact of this vulnerability is a denial-of-service condition where all active authentication sessions fail due to the server disconnecting login processes when invalid base64 SASL data is received.
This can disrupt user access and service availability, especially in environments with concurrent logins.
Mitigation involves installing a fixed version or disabling concurrency in login processes, though the latter may cause a significant performance penalty in large deployments.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should install the fixed version of the affected software.
Alternatively, you can disable concurrency in login processes, but be aware this may cause a heavy performance penalty on large deployments.