CVE-2026-40495

Home/CVE/FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 leak the exact system v

CVE

FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 leak the exact system v

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.

EPSS 0.00055

Schedule remediation

SSVC automatable: yes - attacks can be scripted at scale
⚠ NVD has not scored this CVE yet - manual triage required (common for recent CVEs)

Sigma rules0 YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Vulners Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2026-40495, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

View attack path from CVE-2026-40495

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