CVE-2026-35200: Parse Server has a file upload Content-Type override via extension mismatch

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-06 · updated 2026-07-24
Weakness: CWE-436

Description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 8.6.73 and 9.7.1-alpha.4, a file can be uploaded with a filename extension that passes the file extension allowlist (e.g., .txt) but with a Content-Type header that differs from the extension (e.g., text/html). The Content-Type is passed to the storage adapter without consistency validation. Storage adapters that store and serve the provided Content-Type (such as S3 or GCS) serve the file with the mismatched Content-Type. The default GridFS adapter is not affected because it derives Content-Type from the filename at serving time. This vulnerability is fixed in 8.6.73 and 9.7.1-alpha.4.

Affected products

parse-community parse-server: before 8.6.73; from 9.0.0 before 9.7.1; 9.7.1-alpha1, 9.7.1-alpha2, 9.7.1-alpha3 — fixed in 8.6.73, 9.7.1

How to fix

Upgrade to a fixed version: parse-community parse-server 8.6.73, 9.7.1. Check the vendor advisory for mitigations.

References

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