CVE-2026-28496Public exploitNetwork attack vector

Authenticated code execution via unsandboxed Twig rendering

Published Jun 23, 2026 · Updated Jun 23, 2026

Server-side template injection in FOSSBilling before 0.8.0 allows remote authenticated users to execute code through crafted Twig templates. The string_render API passes the user-supplied _tpl value to renderString(), which invokes Twig createTemplate() without a sandbox and exposes API globals and the dependency injection container. Administrator access to a template-rendering feature is required when exploited alone; successful abuse permits database reads and writes and code execution as the web server process.

CVSS severity9.4
Critical
EPSS probability1.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side template injection in FOSSBilling before 0.8.0 allows remote authenticated users to execute code through crafted Twig templates. The string_render API passes the user-supplied _tpl value to renderString(), which invokes Twig createTemplate() without a sandbox and exposes API globals and the dependency injection container. Administrator access to a template-rendering feature is required when exploited alone; successful abuse permits database reads and writes and code execution as the web server process.

The record

CVE
CVE-2026-28496
Published
Jun 23, 2026
Updated
Jun 23, 2026
Vendor
FOSSBilling
Product
FOSSBilling
Classifications
CWE-1336, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 23, 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=< 0.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FOSSBilling · FOSSBillingversion=< 0.8.0

Published CVSS scores

9.4GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1336Improper Neutralization of Special Elements Used in a Template Engine
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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