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Back to active CVEs
High · CVSS 7.8CVE-2026-104658

Reliance on Untrusted Inputs in a Security Decision in hMailServerCVE-2026-104658

Answer in brief

CVE-2026-104658 records a High severity (CVSS 7.8) vulnerability in Reliance on Untrusted Inputs in a Security Decision in hMailServer. The current sources do not mark it as known exploited. The current feed maps Progressive Robot Ltd/hMailServer (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 8, 2026Updated Oct 8, 2026Source checked Oct 8, 2026First seen by HOL Oct 8, 2026Material review Oct 8, 2026
Upstream Advisory

Key facts

Risk
High · CVSS 7.8
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Progressive Robot Ltd/hMailServer (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Progressive Robot Ltd/hMailServergeneric>=6.3.4 <6.3.66.3.6

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Progressive Robot Ltd/hMailServer.
  2. 2Review the reported fix. Source-reported solution: Upgrade to hMailServer 6.3.6, whose helper takes the unit and the AppImage only from its own root-owned command line, refuses an AppImage request where that names none, confirms that the server has stopped, and verifies, runs and installs only copies it made after the stop, readable by root alone until they have verified. Install 6.3.6 with the package manager (apt or dnf) rather than through the live update. An AppImage run under the path unit keeps the helper script copied to /usr/lib/hmailserver/ when its update units were installed, which the AppImage's own update does not replace: copy 6.3.6's script there and give it --image in a drop-in for hmailserver-update.service. Until then: systemctl disable --now hmailserver-update.path, which turns the apply off while the update check and download go on. Windows, builds with -DHM_LIVE_UPDATE=OFF and the container image are not affected.

Evidence timeline and material changes

  1. Published upstream

    Oct 8, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 8, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Oct 8, 2026

Sources and claim methodology

  • Source referencegitlab.com
  • Source referencegitlab.com
Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Heap-based Buffer Overflow in hMailServerSame progressive robot ltd/hmailserver package
  • Heap-based Buffer Overflow in hMailServerSame progressive robot ltd/hmailserver package
  • Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in hMailServerSame progressive robot ltd/hmailserver package
  • Synchronous Access of Remote Resource without Timeout in hMailServerSame progressive robot ltd/hmailserver package
  • Origin Validation Error in hMailServerSame progressive robot ltd/hmailserver package
  • Missing Authorization in hMailServerSame progressive robot ltd/hmailserver package

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-807
Source
CVE List V5
Source checked
Oct 8, 2026
References
2 linked sources
Open source record