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TI-2026-69502 Aliases CVE-2026-104658

Untrusted inputs in hMailServer updater allow root code execution

Priority LOW 35CWE-807Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Progressive Robot hMailServer 6.3.4 and 6.3.5 on Linux has a flaw in its live-update helper (hmailserver-update). The helper runs as root but trusts a request file written by the hmailserver service account to pick the signature verifier and systemd unit to stop (CWE-807). An attacker running code as that service account can have arbitrary code executed as root where the live update path unit is active.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

The Linux live-update apply helper (hmailserver-update) of Progressive Robot hMailServer 6.3.4 and 6.3.5 runs as root on a request file written by the unprivileged hmailserver service account, and took from that request the program used to verify an AppImage update's signature and the systemd unit to stop before reading the service account's files. An attacker who already runs code as the hmailserver service account, for example through another flaw in the mail server, can therefore have arbitrary code executed as root, on any Linux installation where the live update's path unit is active - the default for the project's .deb and .rpm packages - and on AppImage installations run under that unit.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00114 1st percentileScored 2026-11-07
Fix Fixed hMailServer (Progressive Robot Ltd): 6.3.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Progressive Robot LtdhMailServer6.3.4 to before 6.3.66.3.6Patch availableCNA
  • hMailServer VendorProgressive Robot Ltd Affected 6.3.4 to before 6.3.6 Fixed in 6.3.6 Patch available CNA

Remediation

Upgrade hMailServer to version 6.3.6, the fixed version for the affected 6.3.4 and 6.3.5 releases.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA hMailServer (Progressive Robot Ltd) Fixed in 6.3.6

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Progressive Robot hMailServer 6.3.6

    23 records Highest priority Priority LOW 23 LOW

    Other records, highest priority first

    • TI-2026-69567 Inefficient processing in hMailServer stalls mail deliveryPriority LOW 39
    • TI-2026-69565 Infinite loop in hMailServer MIME handling lets attackers stop mailPriority LOW 39
    • TI-2026-69564 Inefficient DKIM and ARC checks in hMailServer cause denial of servicePriority LOW 39
    Show all 23 records →

Timeline

  1. 2026-10-08 Threatist record created from CVE-2026-104658
  2. 2026-10-08 CISA SSVC decision points changed
  3. 2026-10-08 Priority changed: MEDIUM → LOW

References

Other 2

  • TI-2026-64884 Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in hMailServer CVSS 3.1CRITICAL 9.8
  • TI-2026-76418 Unchecked loop limit in hMailServer lets remote attackers stop mail CVSS 3.1HIGH 7.5
  • TI-2026-69567 Inefficient processing in hMailServer stalls mail delivery CVSS 3.1HIGH 7.5
  • TI-2026-69565 Infinite loop in hMailServer MIME handling lets attackers stop mail CVSS 3.1HIGH 7.5
  • TI-2026-69564 Inefficient DKIM and ARC checks in hMailServer cause denial of service CVSS 3.1HIGH 7.5
  • TI-2026-69562 Inefficient JSON parsing in hMailServer lets attackers halt mail CVSS 3.1HIGH 7.5
See all 41 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences