CVE-2026-53641Public exploitNetwork attack vector

Stored XSS via raw email template literal

Published Jul 6, 2026 · Updated Jul 6, 2026

Stored XSS in FOSSBilling 0.6.0 through 0.7.2 allows remote authenticated users to execute script in clients' browsers via email views. The two client email templates place content_html into an iframe srcdoc JavaScript template literal with Twig raw output, permitting template-expression, backtick, or script-block escape. Administrator access is required to store the payload, and execution occurs when a client opens the email list or message, exposing client-visible data and actions.

CVSS severity4.8
Medium
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in FOSSBilling 0.6.0 through 0.7.2 allows remote authenticated users to execute script in clients' browsers via email views. The two client email templates place content_html into an iframe srcdoc JavaScript template literal with Twig raw output, permitting template-expression, backtick, or script-block escape. Administrator access is required to store the payload, and execution occurs when a client opens the email list or message, exposing client-visible data and actions.

The record

CVE
CVE-2026-53641
Published
Jul 6, 2026
Updated
Jul 6, 2026
Vendor
FOSSBilling
Product
FOSSBilling
Classifications
CWE-838, CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jul 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.6.0, < 0.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

FOSSBilling · FOSSBillingversion=>= 0.6.0, < 0.8.0

Published CVSS scores

4.8GitHub Security AdvisoryCVSS: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 describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-838Inappropriate Encoding for Output Context
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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