CVE-2026-111053: medium-severity vulnerability in FOSSBilling
FOSSBilling: Unauthenticated attacker can probe existence of arbitrary files via guest/system/template_exists
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.9epss 0.4%
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Affected products
FOSSBilling · FOSSBillingRelated CVEs — FOSSBilling
In the same product, most dangerous first.
CVE-2026-28496CRITICALFOSSBilling: Server-side template injection in Twig template rendering enables information disclosure and RCEEPSS 1.9%CVE-2026-27604CRITICALFOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin FunctionsEPSS 1.3%CVE-2026-43920MEDIUMFOSSBilling: Unauthenticated update patcher endpoint allows remote maintenance executionEPSS 0.9%CVE-2026-53647MEDIUMFOSSBilling vulnerable to unauthenticated API key configuration disclosure via guest Serviceapikey get_info endpointEPSS 0.5%CVE-2026-43925MEDIUMFOSSBilling: Mass assignment of group_id in guest client registration allows unauthorized promo code useEPSS 0.5%CVE-2026-33543CRITICALFOSSBilling: Authentication bypass allows unauthenticated administrator creationEPSS 0.4%