GHSA-PP4X-CCXQ-6R33
Vulnerability from github – Published: 2026-09-02 15:10 – Updated: 2026-09-02 15:10Impact
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": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.6.24"
},
"package": {
"ecosystem": "Packagist",
"name": "sulu/sulu"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.6.25"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Packagist",
"name": "sulu/sulu"
},
"ranges": [
{
"events": [
{
"introduced": "3.0.0-alpha1"
},
{
"fixed": "3.0.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-82396"
],
"database_specific": {
"cwe_ids": [
"CWE-79"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-02T15:10:19Z",
"nvd_published_at": "2026-08-31T22:17:22Z",
"severity": "MODERATE"
},
"details": "### Impact\n\nStored Cross Site Scripting (XSS) in the media download endpoint.\n\nThe 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.\n\nEvery 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.\n\nThe 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.\n\n### Patches\n\nFixed 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.\n\n### Workarounds\n\nBlock 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.\n\n```yaml\nsulu_media:\n upload:\n blocked_file_types: [text/html, application/xhtml+xml, image/svg+xml, text/xml, application/xml, text/javascript, application/javascript]\n```\n\nAt 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/*`.\n\nServe uploaded media from a separate origin that does not share the application cookies.\n\nRestrict the media upload permission to trusted users and keep the default SVG sanitizer enabled.",
"id": "GHSA-pp4x-ccxq-6r33",
"modified": "2026-09-02T15:10:19Z",
"published": "2026-09-02T15:10:19Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sulu/sulu/security/advisories/GHSA-pp4x-ccxq-6r33"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82396"
},
{
"type": "WEB",
"url": "https://github.com/sulu/sulu/commit/d061094f5b7bb1d5e974544fce30bede9c7adf8e"
},
{
"type": "PACKAGE",
"url": "https://github.com/sulu/sulu"
},
{
"type": "WEB",
"url": "https://github.com/sulu/sulu/releases/tag/2.6.25"
},
{
"type": "WEB",
"url": "https://github.com/sulu/sulu/releases/tag/3.0.8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Sulu: Stored XSS via media download inline-disposition override"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.