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CVE-2026-126621VulnerabilityPublished

Progressive Robot hMailServer 6.0.0-B1 through 6.3.7 on Windows hands OpenSSL the names of its own TLS files - the

Source GCVE Database

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Authoritative record:CVE-2026-126621· High 7.5

Not known to be exploited · CVSS 7.5 High.

Data as of 11 Nov 2026, 10:05 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitLab)CVSS 3.17.5
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Progressive Robot LtdhMailServerAffected
  • >=6.0.0-B1 <=6.3.7
Fixed in–
GitHubhmailserver/hmailserverpkg:github/hmailserver/hmailserverOther threatsAffected
  • >=6.0.0-B1 <=6.3.7
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The vulnerability requires non-default configurations such as non-ASCII TLS file names and enabled client certificates. Administrators should ensure TLS file names use only ASCII characters, disable client certificate authentication on ports unless necessary, and disable object store and ACME features if not in use. Monitor vendor advisories for official patches or updates addressing this issue.

Description

Progressive Robot hMailServer versions 6.0.0-B1 through 6.3.7 on Windows improperly handle TLS file names by passing them as Latin-1 bytes to OpenSSL, which interprets them as UTF-8. This mismatch allows a local attacker with file creation permissions to substitute TLS-related files, enabling unauthorized client certificate acceptance, interception and modification of stored messages, exposure of ACME client private keys, or denial of TLS port startup. The vulnerability requires non-default configurations such as non-ASCII file names and enabled client certificates. Linux builds are not affected.

References

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