Parse Server 9.0.0 Stored XSS via malformed Content-Type
Parse Server is affected by a stored cross-site scripting (XSS) vulnerability in versions >= 9.0.0, < 9.10.0-alpha.2 and <= 8.6.83. When an uploaded file's extension is not recognized by the mime package, Parse Server preserves the client-supplied Content-Type. A malformed Content-Type that is not a valid type/subtype media type (e.g., 'image', 'image/', or 'image//svg+xml') bypasses the fileUpload.fileExtensions blocklist and is stored unchanged. On storage adapters that persist and serve the uploaded Content-Type (such as Amazon S3, Google Cloud Storage, or Azure Blob Storage), a browser cannot parse the malformed value and falls back to MIME-sniffing; a file whose body begins with HTML is rendered as HTML, executing embedded script in the application's origin against other users who open the file URL. The default GridFS storage adapter is not affected. Fixed in 9.10.0-alpha.2 and 8.6.84.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-61448
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 18:37 UTC · Revision 1
Source evidence
Parse Server 9.0.0 Stored XSS via malformed Content-Type
core-osv · Original sourcePublished 11 Jul 2026, 13:01 UTC
Parse Server is affected by a stored cross-site scripting (XSS) vulnerability in versions >= 9.0.0, < 9.10.0-alpha.2 and <= 8.6.83. When an uploaded file's extension is not recognized by the mime package, Parse Server preserves the client-supplied Content-Type. A malformed Content-Type that is not a valid type/subtype media type (e.g., 'image', 'image/', or 'image//svg+xml') bypasses the fileUpload.fileExtensions blocklist and is stored unchanged. On storage adapters that persist and serve the uploaded Content-Type (such as Amazon S3, Google Cloud Storage, or Azure Blob Storage), a browser cannot parse the malformed value and falls back to MIME-sniffing; a file whose body begins with HTML is rendered as HTML, executing embedded script in the application's origin against other users who open the file URL. The default GridFS storage adapter is not affected. Fixed in 9.10.0-alpha.2 and 8.6.84.
osv:CVE-2026-61448
Complete source record
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"url": "https://osv.dev/vulnerability/CVE-2026-61448",
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"title": "Parse Server 9.0.0 Stored XSS via malformed Content-Type",
"summary": "Parse Server is affected by a stored cross-site scripting (XSS) vulnerability in versions >= 9.0.0, < 9.10.0-alpha.2 and <= 8.6.83. When an uploaded file's extension is not recognized by the mime package, Parse Server preserves the client-supplied Content-Type. A malformed Content-Type that is not a valid type/subtype media type (e.g., 'image', 'image/', or 'image//svg+xml') bypasses the fileUpload.fileExtensions blocklist and is stored unchanged. On storage adapters that persist and serve the uploaded Content-Type (such as Amazon S3, Google Cloud Storage, or Azure Blob Storage), a browser cannot parse the malformed value and falls back to MIME-sniffing; a file whose body begins with HTML is rendered as HTML, executing embedded script in the application's origin against other users who open the file URL. The default GridFS storage adapter is not affected. Fixed in 9.10.0-alpha.2 and 8.6.84.",
"evidence": "osv:CVE-2026-61448",
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"modified": "2026-10-28T02:30:38.172829938Z",
"provider": "osv",
"references": [
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"source_id": "core-osv",
"document_id": 505762,
"published_at": "2026-07-11T13:01:05.852+00:00"
}