IM
IronMonkey Threat Research

CVE-2026-40495 MEDIUM

Published: 2026-06-03 | Last Modified: 2026-06-03 | Status: Received

Description

FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 leak the exact system version through asset cache buster parameters in HTML output, bypassing the `hide_version_public` security setting. The FOSSBilling version is embedded in the query string of every `<script>` and `<link>` tag generated by the `script_tag` and `stylesheet_tag` Twig filters. This information is visible to all visitors — including unauthenticated guests — on every page, regardless of whether the `hide_version_public` setting is enabled. The `X-FOSSBilling-Version` HTTP header and the `guest.system.version` API endpoint correctly honour the `hide_version_public` setting, but the asset cache buster parameters were overlooked. Knowledge of the exact FOSSBilling version makes it significantly easier for malicious actors to identify known vulnerabilities applicable to a given installation and craft targeted exploits. While not a direct vulnerability on its own, it undermines the intended protection offered by the `hide_version_public` setting and facilitates reconnaissance. Version 0.8.0 contains a patch. There is no practical workaround that removes the version from asset URLs without modifying source code.

CVSS Metrics

Base Score: 6.9 (MEDIUM)

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack VectorNETWORK
Attack ComplexityLOW
Attack RequirementsNONE
Privileges RequiredNONE
User InteractionNONE
Vulnerability ConfidentialityLOW
Vulnerability IntegrityNONE
Vulnerability AvailabilityNONE
Subsequent ConfidentialityNONE
Subsequent IntegrityNONE
Subsequent AvailabilityNONE

Source: [email protected]

Type: Secondary

Weaknesses

Source Type Description
[email protected] Primary
en CWE-200
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