PatchTheCVECVE-2025-59028: When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active
CVE-2025-59028 is a medium-severity flaw (CVSS 5.3) affecting dovecot, dovecot. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 60%) |
| CISA exploited list | No |
| Weakness | CWE-20 |
| Published | 2026-03-27 |
| Last modified | 2026-10-07 |
Last updated 2026-10-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2025-59028?
dovecot: upgrade to 2.4.3; dovecot: upgrade to 3.1.2. Exact commands for each OS are on this page.
Is CVE-2025-59028 being exploited?
CVE-2025-59028 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2025-59028 affect?
CVE-2025-59028 affects dovecot, dovecot. Severity is medium (CVSS 5.3). 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 fi
How urgent is CVE-2025-59028?
Priority 34/100. Remotely exploitable, no login, no user action
Software pages
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