CVE-2026-61448: Unrestricted Upload of File with Dangerous Type in parse-community parse-server
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.
AI Analysis
Technical Summary
Parse Server suffers from a stored XSS vulnerability in versions >=9.0.0 <9.10.0-alpha.2 and <=8.6.83 due to improper handling of uploaded files with unrecognized extensions. When the mime package does not recognize the file extension, the server preserves the client-supplied Content-Type header, even if malformed (e.g., 'image', 'image/', 'image//svg+xml'). This malformed Content-Type bypasses the fileUpload.fileExtensions blocklist and is stored as-is. On storage adapters that persist and serve the Content-Type header (such as Amazon S3, Google Cloud Storage, Azure Blob Storage), browsers fail to parse the malformed Content-Type and revert to MIME-sniffing. If the file content begins with HTML, it is rendered as HTML, executing embedded scripts in the application's origin context, potentially affecting users who access the file URL. The default GridFS adapter is not vulnerable. The vulnerability is fixed in versions 9.10.0-alpha.2 and 8.6.84.
Potential Impact
The vulnerability allows an attacker to upload files with dangerous or malformed Content-Type headers that bypass file extension restrictions. This can lead to stored cross-site scripting (XSS) attacks when browsers MIME-sniff the file and execute embedded scripts in the context of the application's origin. This impacts users who open the malicious file URL, potentially exposing them to script-based attacks. The default GridFS storage adapter is not affected, but cloud storage adapters that serve the Content-Type header are vulnerable. The CVSS 4.0 score is low (2.1), reflecting limited impact and required privileges.
Mitigation Recommendations
A fix is available in Parse Server versions 9.10.0-alpha.2 and 8.6.84. Users should upgrade to these or later versions to remediate the vulnerability. Since this is a cloud-hosted service scenario, the vendor manages remediation for the cloud-hosted service; users should verify with the vendor advisory for current patch status. Until patched, restrict file uploads to recognized safe types and consider additional validation on Content-Type headers to prevent malformed values.
CVE-2026-61448: Unrestricted Upload of File with Dangerous Type in parse-community parse-server
Description
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.
CVSS v4.0
Score 2.1low
Affected software
pkg:github/parse-community/parse-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Parse Server suffers from a stored XSS vulnerability in versions >=9.0.0 <9.10.0-alpha.2 and <=8.6.83 due to improper handling of uploaded files with unrecognized extensions. When the mime package does not recognize the file extension, the server preserves the client-supplied Content-Type header, even if malformed (e.g., 'image', 'image/', 'image//svg+xml'). This malformed Content-Type bypasses the fileUpload.fileExtensions blocklist and is stored as-is. On storage adapters that persist and serve the Content-Type header (such as Amazon S3, Google Cloud Storage, Azure Blob Storage), browsers fail to parse the malformed Content-Type and revert to MIME-sniffing. If the file content begins with HTML, it is rendered as HTML, executing embedded scripts in the application's origin context, potentially affecting users who access the file URL. The default GridFS adapter is not vulnerable. The vulnerability is fixed in versions 9.10.0-alpha.2 and 8.6.84.
Potential Impact
The vulnerability allows an attacker to upload files with dangerous or malformed Content-Type headers that bypass file extension restrictions. This can lead to stored cross-site scripting (XSS) attacks when browsers MIME-sniff the file and execute embedded scripts in the context of the application's origin. This impacts users who open the malicious file URL, potentially exposing them to script-based attacks. The default GridFS storage adapter is not affected, but cloud storage adapters that serve the Content-Type header are vulnerable. The CVSS 4.0 score is low (2.1), reflecting limited impact and required privileges.
Mitigation Recommendations
A fix is available in Parse Server versions 9.10.0-alpha.2 and 8.6.84. Users should upgrade to these or later versions to remediate the vulnerability. Since this is a cloud-hosted service scenario, the vendor manages remediation for the cloud-hosted service; users should verify with the vendor advisory for current patch status. Until patched, restrict file uploads to recognized safe types and consider additional validation on Content-Type headers to prevent malformed values.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-07-09T14:06:14.016Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
Threat ID: 6a52461768715ace43df4b32
Added to database: 07/11/2026, 13:33:11 UTC
Last enriched: 07/18/2026, 14:56:38 UTC
Last updated: 08/24/2026, 22:52:12 UTC
Views: 95
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