CVE-2025-66039Public exploitNetwork attack vector

Unauthenticated admin access via unvalidated Basic credentials

Published Dec 9, 2025 · Updated Feb 26, 2026

Authentication bypass in FreePBX Framework before 16.0.44 and 17.0.1 through 17.0.22 allows remote attackers to access the admin panel. The webserver branch in gui_auth.php trusts PHP_AUTH_USER from a Basic Authorization header and establishes the user's session without validating the supplied password. Exploitation requires the non-default AUTHTYPE webserver setting and a known or guessed username, granting access to privileged administrative endpoints as that account.

CVSS severity9.3
Critical
EPSS probability3.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in FreePBX Framework before 16.0.44 and 17.0.1 through 17.0.22 allows remote attackers to access the admin panel. The webserver branch in gui_auth.php trusts PHP_AUTH_USER from a Basic Authorization header and establishes the user's session without validating the supplied password. Exploitation requires the non-default AUTHTYPE webserver setting and a known or guessed username, granting access to privileged administrative endpoints as that account.

The record

CVE
CVE-2025-66039
Published
Dec 9, 2025
Updated
Feb 26, 2026
Vendor
FreePBX
Product
Framework
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 16.0.44
  2. Affected versionversion=>= 17.0.1, < 17.0.23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreePBX · Frameworkversion=< 16.0.44; version=>= 17.0.1, < 17.0.23

Published CVSS scores

9.3FreePBXCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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