# CVE-2026-73665 — FreePBX ucp

> As of 2026-08-13, CVE-2026-73665 is a Critical-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in FreePBX ucp, CVSS v4.0 9.3, EPSS 0.2% (21.9th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-73665 as of 2026-08-13; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-08-13

## What is CVE-2026-73665?

FreePBX is an open source IP PBX. Prior to 17.0.9, the UCP Node server on ports 8001 and 8003 uses io.use(checkAuth) in node/lib/server.js, but Socket.IO version 4 applies that middleware only to the default namespace. An unauthenticated client can connect to custom namespaces that do not consistently invoke checkAuth in node/lib/auth.js and send crafted event values containing carriage-return or newline characters through the Asterisk Manager Interface action path patched by node/lib/asterisk-manager-patch.js, allowing arbitrary commands to execute as the asterisk service user. This issue is fixed in version 17.0.9.

The record classifies CVE-2026-73665 under weakness class [CWE-862](https://intel.threadlinqs.com/cwe/CWE-862). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 53 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 9.3 — Critical (derived from score) (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 21.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-13

## Is CVE-2026-73665 being exploited?

It currently carries a trending score of 35 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **FreePBX**: ucp

## How to fix CVE-2026-73665

No vendor patch reference has been recorded for CVE-2026-73665 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-73665

No threat campaign in the Threadlinqs corpus currently references CVE-2026-73665, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-08-15. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/FreePBX/security-reporting/security/advisories/GHSA-37j8-fhxx-9vhp)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-73665
Full detection coverage and IOCs for threats exploiting CVE-2026-73665 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp