How severe is CVE-2026-82396?

CVE-2026-82396 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-82396?

CVE-2026-82396 affects the following packages: sulu/sulu (Packagist), sulu/sulu (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-82396?

Update sulu/sulu to 2.6.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-82396 is resolved across your whole dependency graph.

How do I detect CVE-2026-82396 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sulu/sulu, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-82396 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-82396 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-82396 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-82396?

CVE-2026-82396 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 21th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-82396?

CVE-2026-82396 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-82396 published, and has it been updated?

CVE-2026-82396 was published on August 31, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2026-82396 — sulu

MEDIUMFix: sulu/sulu@d061094

CVE-2026-82396 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in sulu/sulu. A fix is available for sulu/sulu — see the affected versions and patch details below.

Sulu: Stored XSS via media download inline-disposition override

Also known asGHSA-pp4x-ccxq-6r33

Published

Aug 31, 2026

Updated

Sep 10, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-82396.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs21th percentile — riskier than 21% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-82396 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 390,400 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

🐘sulu/sulu🐘sulu/sulu

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

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.

Patches

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.

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.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`sulu/sulu`	all versions	2.6.25`composer require sulu/sulu:^2.6.25`
🐘Packagist	`sulu/sulu`	≥ 3.0.0-alpha1&&< 3.0.8	3.0.8`composer require sulu/sulu:^3.0.8`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sulu/sulu, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sulu/sulu to 2.6.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-82396 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### 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 t