Summary
Sulu: Stored XSS via media download inline-disposition override
Workarounds
Block scriptable uploads by MIME type through sulu_media.upload.blocked_file_types. This stops new uploads only, so existing media has to be reviewed separately.
sulu_media:
upload:
blocked_file_types: [text/html, application/xhtml+xml, image/svg+xml, text/xml, application/xml, text/javascript, application/javascript]
At the web server or reverse proxy, force Content-Disposition: attachment and add X-Content-Type-Options: nosniff and a restrictive Content-Security-Policy on the paths /media/*/download/* and /admin/media/*/download/*.
Serve uploaded media from a separate origin that does not share the application cookies.
Restrict the media upload permission to trusted users and keep the default SVG sanitizer enabled.
Impact
Stored Cross Site Scripting (XSS) in the media download endpoint.
The download route (/media/{id}/download/{slug} and its admin variant) accepts the query parameter ?inline=1. When it is present, the response is sent with the header Content-Disposition: inline for any MIME type, which overrides the disposition rules the server would otherwise apply. By default, HTML and other scriptable uploads are not blocked, the file is served on the application origin with its stored Content-Type, and no X-Content-Type-Options or Content-Security-Policy header is sent. Because of this, an attacker can upload an HTML file and build a link that runs their own JavaScript in the context of the Sulu origin.
Every installation where users who are not fully trusted can upload media is affected. This includes editors who hold the media add permission. Such an editor can store a payload that runs in the authenticated session of anyone who opens the link, including an administrator, which allows theft of the session and credentials and lets the attacker act as the victim.
The problem is present on the 2.6 and 3.0 branches and goes back to the introduction of the ?inline override in 2017. It is not the same as CVE-2024-47617, which was a reflected XSS through the slug and is already fixed.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2026-82396 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.6.25, 3.0.8); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in 2.6.25 and 3.0.8. The download route now forces Content-Disposition: attachment for MIME types a browser renders as a document (text/html, application/xhtml+xml, text/xml, application/xml), even when ?inline=1 is requested. Inline viewing is unchanged for safe types such as PDF and images.
Frequently Asked Questions
- What is CVE-2026-82396? CVE-2026-82396 is a medium-severity cross-site scripting (XSS) vulnerability in sulu/sulu (composer), affecting versions <= 2.6.24. It is fixed in 2.6.25, 3.0.8. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2026-82396? CVE-2026-82396 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of sulu/sulu are affected by CVE-2026-82396? sulu/sulu (composer) versions <= 2.6.24 is affected.
- Is there a fix for CVE-2026-82396? Yes. CVE-2026-82396 is fixed in 2.6.25, 3.0.8. Upgrade to this version or later.
- Is CVE-2026-82396 exploitable, and should I be worried? Whether CVE-2026-82396 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-82396 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-82396?
- Upgrade
sulu/suluto 2.6.25 or later - Upgrade
sulu/suluto 3.0.8 or later
- Upgrade