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Information ExposureWeakness · CWE-200

CVE-2026-40495

MEDIUM · 6.9 CVSS v4.0 Published 2026-06-03
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

FOSSBilling versions prior to 0.8.0 embed the exact system version in cache buster query parameters for all `<script>` and `<link>` tags generated by Twig filters (script_tag and stylesheet_tag), bypassing the hide_version_public security setting and exposing version information to all visitors including unauthenticated guests.

MitigationUpgrade to FOSSBilling version 0.8.0 or later which contains the patch to honor the hide_version_public setting in asset URLs.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed FOSSBilling version
    Locate the version file in the FOSSBilling installation directory (commonly version.php, composer.json, or a src/Version.php file) and read the defined version number
    Affected if The version is lower than 0.8.0 (e.g., 0.7.x, 0.6.x, etc.)
  2. Check hide_version_public configuration setting
    Locate the configuration file (usually config.php or settings/database.php) and search for the 'hide_version_public' parameter to determine its current value
    Affected if The setting exists but version information still appears in asset URLs despite this setting being enabled
  3. Inspect HTML source for version disclosure in assets
    Visit any public-facing page of the FOSSBilling site, view the page source (right-click > View Page Source), and examine the src attributes of <script> tags and href attributes of <link> tags for cache buster query parameters (e.g., ?v= or ?version=)
    Affected if Version numbers appear in query parameters of script or stylesheet URLs (such as ?v=0.7.5 or ?version=0.7.5)

The environment is affected if FOSSBilling version is below 0.8.0 and version information is visible in cache buster parameters of script/link tags on any public page.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to FOSSBilling version 0.8.0 or later which contains the patch to honor the hide_version_public setting in asset URLs.

Recommended fix High confidence

0.8.0

  1. Backup your entire FOSSBilling installation including database and configuration files
  2. Review the FOSSBilling 0.8.0 release notes for any specific upgrade instructions or migration steps
  3. Download FOSSBilling version 0.8.0 from the official repository
  4. Test the upgrade in a staging environment before applying to production
  5. Apply the upgrade following standard FOSSBilling upgrade procedures
  6. Verify that the version is no longer exposed in asset cache buster parameters by inspecting HTML source of any page
Caveat Review release notes for any breaking changes between your current version and 0.8.0

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,980
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40495 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data