CVE-2026-55778: CWE-434: Unrestricted Upload of File with Dangerous Type in parse-community parse-server
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.
AI Analysis
Technical Summary
CVE-2026-55778 describes a vulnerability in parse-community's parse-server where the default fileUpload.fileExtensions blocklist can be bypassed by uploading files with non-standard or compound extensions and dangerous content types. This allows attackers to upload active content that storage adapters such as Amazon S3 and Google Cloud Storage may serve, leading to stored cross-site scripting (XSS). The vulnerability affects versions prior to 8.6.81 and includes 9.9.1-alpha.11. The issue is resolved in versions 8.6.81 and 9.9.1-alpha.11.
Potential Impact
An attacker can bypass file extension restrictions to upload files containing active content, which may be served by storage adapters like S3 and GCS. This can lead to stored cross-site scripting vulnerabilities, potentially impacting users who access the malicious content. The CVSS 4.0 score is low (2.1), reflecting limited impact and exploit complexity.
Mitigation Recommendations
A patch is available and the vulnerability is fixed in parse-server versions 8.6.81 and 9.9.1-alpha.11. Users should upgrade to these or later versions to remediate the issue. Since this is a cloud-hosted service, the vendor manages remediation for the cloud environment; users should verify their deployment uses patched versions. No additional mitigation actions are specified by the vendor advisory.
CVE-2026-55778: CWE-434: Unrestricted Upload of File with Dangerous Type in parse-community parse-server
Description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.
CVSS v4.0
Score 2.1low
Affected software
pkg:npm/parse-community/parse-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-55778 describes a vulnerability in parse-community's parse-server where the default fileUpload.fileExtensions blocklist can be bypassed by uploading files with non-standard or compound extensions and dangerous content types. This allows attackers to upload active content that storage adapters such as Amazon S3 and Google Cloud Storage may serve, leading to stored cross-site scripting (XSS). The vulnerability affects versions prior to 8.6.81 and includes 9.9.1-alpha.11. The issue is resolved in versions 8.6.81 and 9.9.1-alpha.11.
Potential Impact
An attacker can bypass file extension restrictions to upload files containing active content, which may be served by storage adapters like S3 and GCS. This can lead to stored cross-site scripting vulnerabilities, potentially impacting users who access the malicious content. The CVSS 4.0 score is low (2.1), reflecting limited impact and exploit complexity.
Mitigation Recommendations
A patch is available and the vulnerability is fixed in parse-server versions 8.6.81 and 9.9.1-alpha.11. Users should upgrade to these or later versions to remediate the issue. Since this is a cloud-hosted service, the vendor manages remediation for the cloud environment; users should verify their deployment uses patched versions. No additional mitigation actions are specified by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-17T14:40:28.379Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
Threat ID: 6a4ebdf5c9d9e3dbe3bf8b0a
Added to database: 07/08/2026, 21:15:33 UTC
Last enriched: 07/16/2026, 10:11:40 UTC
Last updated: 08/22/2026, 22:52:14 UTC
Views: 80
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