CVE-2026-55778

Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist

Published: Jul 8, 2026Updated: Jul 10, 2026 Sources: CVE List NVDCWE-434

N/ACVSS

NVD MITRE

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.

No summary for this CVE yet.

Weaknesses

CWE-434

Affected Products

parse-community

oss-projectaka parse-server, parse, parse server

parse-serverLibraryLibrary

OSS Libraries / npm

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

3 techniques

Command and Control

Initial Access

Persistence

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References

https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a

github.com

https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50

github.com

https://github.com/parse-community/parse-server/pull/10505

github.com

and 4 more references View all →

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