Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-53641

Severity CVSS v4.0:
MEDIUM
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
06/07/2026
Last modified:
06/07/2026

Description

FOSSBilling is a free, open-source billing and client management system. Versions 0.6.0 through 0.7.2 have a stored cross-site scripting (XSS) vulnerability in the client-facing email history views of FOSSBilling. Email HTML content (`content_html`) is rendered into a JavaScript template literal using the `|raw` filter, bypassing all output escaping. An attacker with admin access can inject malicious JavaScript payloads into email content that execute in the browser of any client who views their email history. Version 0.8.0 contains a fix. Some workarounds are available. Restrict admin account access, audit email content in the database for suspicious payloads, and/or monitor client accounts for unusual activity.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 4.80 MEDIUM
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): None
Privileges Required (PR): High
User Interaction (UI): Passsive
Confidentiality (VC): Low
Integrity (VI): Low
Availability (VA): None
Confidentiality (SC): Low
Integrity (SI): Low
Availability (SA): None

Base Score 4.0
4.80
Severity 4.0
MEDIUM

References to Advisories, Solutions, and Tools