CVE.org (no NVD analysis yet)· CNA GitLab

CVE-2026-126626: Overly Restrictive Account Lockout Mechanism in hMailServer

MediumCVSS 5.3 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 21/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.52% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The web services listener of Progressive Robot hMailServer 6.3.3 through 6.3.7 counts every failed CardDAV, CalDAV or Autodiscover sign-in from a proxy it trusts - one on the same machine, or one named in WebServicesTrustedProxies, whose X-Forwarded-Proto it believes - against the proxy's own address, which allows a remote unauthenticated attacker who can reach the proxy to have that address banned from the server's mail listeners. The listener, off by default (WebServicesHttpPort and WebServicesHttpsPort 0), signs an account in with HTTP Basic over HTTPS for CardDAV from 6.3.3 and for CalDAV and Outlook Autodiscover from 6.3.4. Behind a TLS-terminating proxy, which the server trusts when it is on the same machine or named in WebServicesTrustedProxies, the listener takes the client's HTTPS from the proxy's X-Forwarded-Proto header, but it does not believe X-Forwarded-For and sees the proxy's address for every client. Each failed sign-in counted towards the auto-ban against that address, so that failed sign-ins through the proxy from anybody, under any user name, reaching MaxInvalidLogonAttempts (3 within 30 minutes by default) wrote an IP range that refused the proxy's address at the SMTP, POP3, IMAP and ManageSieve listeners for AutoBanMinutes (60 by default), and could write it again each time it lapsed. For a proxy on the same machine that address is the loopback address, so that a webmail on that machine, local scripts that submit mail and the other local clients of the mail listeners were shut out; for a proxy at another address that also carries mail, every mail client behind it was. Such a proxy forwarding to the listener's HTTPS port, re-encrypting, was counted against in the same way, and listing it in WebServicesTrustedProxies did not spare it. The auto-ban is on by default and AutoBanNeverBan, which spares an address, is empty by default; the listener itself went on serving the proxy.

EUVD-2026-123338

Published: Nov 11, 2026
Updated: Nov 12, 2026
EPSS: 0.5% · 44th percentile
CWE: CWE-645

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Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

CNA vs NVD score

NVD: —
CNA · GitLab: 5.3; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Noroxi analysis

What does it mean in your environment?

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Affected systems

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitLab). Independent of NVD's CPE analysis and usually ahead of it.

Progressive Robot Ltd hMailServer
- 6.3.3 and later · up to and including 6.3.7affected · semver

Same product

progressive robot ltd: all records

Other highest-scoring records for the same primary product.

CVE-2026-100741Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in hMailServer
40Plan
CVE-2026-126617Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') in hMailServer
35Monitor
CVE-2026-114489Missing Authorization in hMailServer
32Monitor

Published before and after this one in the same product

← EarlierCVE-2026-126623Nov 11, 2026 · Inefficient Algorithmic Complexity in hMailServer
30Monitor
← EarlierCVE-2026-126624Nov 11, 2026 · Unverified Ownership in hMailServer
29Monitor
← EarlierCVE-2026-126625Nov 11, 2026 · Incorrect Default Permissions in hMailServer
26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.