CVE-2026-55778

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.

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50 https://github.com/parse-community/parse-server/pull/10505 https://github.com/parse-community/parse-server/pull/10506 https://github.com/parse-community/parse-server/releases/tag/8.6.81 https://github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11 https://github.com/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93

Frequently Asked Questions

What is CVE-2026-55778? +

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.

How do I check if I'm vulnerable to CVE-2026-55778? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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