Medium 6.9Published Oct 19, 2026

CVE-2026-111053FOSSBilling: Unauthenticated attacker can probe existence of arbitrary files via guest/system/template_exists

Updated under an hour ago (2026-10-21 03:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

FOSSBilling is an open source billing and client-management platform. From 0.1.0 until 0.8.7, the unauthenticated api/guest/system/template_exists endpoint permits path traversal because templateExists uses Path::join on the attacker-controlled file parameter without rejecting .. sequences or verifying that the resolved path remains inside the active theme directory. The trigger is an unauthenticated request to guest/system/template_exists containing traversal sequences in the file parameter. An attacker can submit traversal sequences in the file parameter and observe the returned boolean to determine whether arbitrary files or directories exist on the server. The oracle does not disclose file contents. This issue is fixed in version 0.8.7.

CVSS: 6.9 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-22, CWE-200
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 19, 2026

Affected products

Affected products

FOSSBilling FOSSBilling fossbilling:fossbilling (from the name)	from 0.1.0, < 0.8.7	CNA record

References

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-fm3x-cx5r-wwgpx-refsource-confirm
https://github.com/FOSSBilling/FOSSBilling/pull/4221x-refsource-misc
https://github.com/FOSSBilling/FOSSBilling/commit/e6ca7731c6bce406aba11900a4450e89c4ebdb01x-refsource-misc
https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.7x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.