The auto-ban of Progressive Robot hMailServer 6.0.0-B1 through 6.3.7 can be kept from banning an address after
Source GCVE Database
Not known to be exploited · CVSS 5.3 Medium.
Data as of 11 Nov 2026, 10:17 UTC
Thin evidence
One scorer or none| CNA (GitLab) | CVSS 3.1 | 5.3 |
|---|
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Progressive Robot LtdhMailServer | Affected
| Fixed in– |
GitHubhmailserver/hmailserverpkg:github/hmailserver/hmailserverOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should monitor vendor advisories for updates. Until a fix is available, consider disabling or limiting the use of affected protocols where possible, especially ManageSieve, CalDAV/CardDAV, and REST API which are off by default. Adjust MaxInvalidLogonAttempts to a lower value to reduce the window for guessing. Review server logs for repeated HM5032 and HM6099 errors indicating failed ban saves. Implement additional external protections such as network-level rate limiting or firewall rules to mitigate brute-force attempts.
Description
Progressive Robot hMailServer versions 6.0.0-B1 through 6.3.7 contain a vulnerability in the auto-ban mechanism that allows an attacker to bypass IP address banning after repeated failed login attempts. This flaw arises from how the server names and stores banned IP ranges based on usernames, leading to failures in saving bans when usernames are very long or contain certain characters such as NUL. Consequently, an attacker connecting from multiple IP addresses can continue guessing passwords over various protocols without being effectively banned.