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  4. CVE 2026 104659 origin validation error in hmailserver
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Back to active CVEs
High · CVSS 7.5CVE-2026-104659

Origin Validation Error in hMailServerCVE-2026-104659

Answer in brief

CVE-2026-104659 records a High severity (CVSS 7.5) vulnerability in Origin Validation Error 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 7.5
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 7.5. 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>=6.0.0 <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 REST listener refuses an unexpected Host before any authentication and delays a wrong administrator password on every route. Until then: keep the REST API off (RestApiPort 0, the default) or reach it only through a reverse proxy that checks the Host header; give the administrator a long random password and enrol its second factor; do not browse the web from the server.

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

Missing Host header validation and missing throttling of failed administrator sign-ins in the REST API listener of Progressive Robot hMailServer 6.0.0 through 6.3.5 allow a remote attacker to brute-force the server administrator's password through the administrator's own browser by DNS rebinding. The listener, which is off by default and bound to the loopback when enabled, answered requests whatever their Host header named, and a failed sign-in with the administrator's password from the loopback was neither auto-banned nor delayed. A web page whose host name the attacker rebinds to 127.0.0.1, opened in a browser on the server, can therefore send authenticated requests to the listener, read the answers and try administrator passwords at full speed until one is accepted, giving the attacker full administrative control of the mail server.

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
  • Reliance on Untrusted Inputs in a Security Decision 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-346
Source
CVE List V5
Source checked
Oct 8, 2026
References
2 linked sources
Open source record