EUVD-2026-17473
GHSA-vpj2-qq7w-5qq6
CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
4Description
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.67 and 9.7.0-alpha.11, an attacker can bypass Cloud Function validator access controls by appending "prototype.constructor" to the function name in the URL. When a Cloud Function handler is declared using the function keyword and its validator is a plain object or arrow function, the trigger store traversal resolves the handler through its own prototype chain while the validator store fails to mirror this traversal, causing all access control enforcement to be skipped. This allows unauthenticated callers to invoke Cloud Functions that are meant to be protected by validators such as requireUser, requireMaster, or custom validation logic. This issue has been patched in versions 8.6.67 and 9.7.0-alpha.11.
Analysis
Parse Server Cloud Function validator bypass allows unauthenticated remote attackers to execute protected server-side functions by exploiting prototype chain traversal. Attackers append 'prototype.constructor' to Cloud Function URLs to circumvent access controls (requireUser, requireMaster, custom validators), enabling unauthorized execution of backend business logic. …
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Remediation
Within 24 hours: Inventory all Parse Server instances and document current versions (8.6.67, 9.7.0-alpha.11 and later unaffected). Within 7 days: Prioritize evaluation of available mitigation strategies from Parse Server maintainers; implement network segmentation to restrict Cloud Function endpoint access if available. …
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External POC / Exploit Code
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