CVE-2026-53641

MEDIUMCVSS 4.8/10EPSS 0.29%

Last modified

CVE-2026-53641 is a medium-severity vulnerability rated 4.8/10 on the CVSS scale. 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. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 4.0
4.8/10

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/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

EPSS Probability
0.29%

20.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
FOSSBillingFOSSBilling>= 0.6.0, < 0.8.0

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-53641?
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.
How severe is CVE-2026-53641?
CVE-2026-53641 has a CVSS score of 4.8/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.
How do I fix CVE-2026-53641?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST