CVE-2026-40520Network attack vector

Authenticated OS command execution via unescaped GraphQL fields

Published Apr 21, 2026 · Updated Apr 21, 2026

Command injection in FreePBX PBX API 17.0.8 and earlier allows remote authenticated users to execute arbitrary OS commands via GraphQL. The initiateGqlAPIProcess() function concatenates GraphQL moduleOperations fields into a shell_exec() command without quoting or escaping them. A valid OAuth2 bearer token and GraphQL access are required; injected commands run with the privileges of the web server user.

CVSS severity8.6
High
EPSS probability1.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in FreePBX PBX API 17.0.8 and earlier allows remote authenticated users to execute arbitrary OS commands via GraphQL. The initiateGqlAPIProcess() function concatenates GraphQL moduleOperations fields into a shell_exec() command without quoting or escaping them. A valid OAuth2 bearer token and GraphQL access are required; injected commands run with the privileges of the web server user.

The record

CVE
CVE-2026-40520
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
FreePBX
Product
PBX API
Classifications
CWE-78, T1059.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 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=0 <=17.0.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FreePBX · PBX APIversion=0 <=17.0.8

Published CVSS scores

7.2VulnCheckCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
8.6VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell

Public exploit references

No public exploit references are available in this record.

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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