CVE-2026-119569: Parse Server prototype pollution denial of service

CVE-2026-119569 · Severity: medium · CVSS 5.3 · Published 2026-10-30

Parse Server, a backend framework that handles data storage and access control for applications, contains a vulnerability where authenticated users with write access can send specially crafted field names that corrupt the server's core functions. When exploited, this causes all requests to fail until the server is restarted, disrupting service for all application users.

Technologies: Parse Community Parse Server. Vendors: Parse Community.

Quick answers

Is CVE-2026-119569 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-119569 being exploited in the wild.
How severe is CVE-2026-119569?
Medium severity, with a CVSS score of 5.3, published 30 October 2026.
Which products and versions are affected?
Parse Community Parse Server before 8.6.108 and 9.0.0 before 9.10.5-alpha.9.
Is there a fix for CVE-2026-119569?
Yes: fixed in Parse Server 8.6.108, 9.10.5-alpha.9. Until then: Maintain the default requestKeywordDenylist configuration, which already rejects the highest-impact keys (__proto__, constructor). As a partial mitigation, extend the denylist to also reject keys such as toString, valueOf, and hasOwnProperty; however, upgrading is recommended as there is no complete configuration-only workaround for the dot notation vector.</anigation> <parameter name="timeline">[ { "kind": "disclosed", "at": "2026-10-15" }, { "kind": "advisory", "at": "2026-10-30" } ] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-119569 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-119569?
Check whether you run Parse Community Parse Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: Parse Server 8.6.108, 9.10.5-alpha.9

Maintain the default requestKeywordDenylist configuration, which already rejects the highest-impact keys (__proto__, constructor). As a partial mitigation, extend the denylist to also reject keys such as toString, valueOf, and hasOwnProperty; however, upgrading is recommended as there is no complete configuration-only workaround for the dot notation vector.</anigation> <parameter name="timeline">[ { "kind": "disclosed", "at": "2026-10-15" }, { "kind": "advisory", "at": "2026-10-30" } ]

Technical details

This is a prototype pollution vulnerability (CWE-1321) in Parse Server's write request handling and ACL processing. Clients with class write access can exploit dot notation keys or ACL entry names matching built-in object members (like __proto__, constructor, toString) to pollute the JavaScript prototype chain. The vulnerability requires low privileges (class write access) and network access; unpatched versions before 8.6.108 and 9.0.0–9.10.5-alpha.9 are affected across all configured applications in multi-tenant deployments.

Affected products

  • Parse Community Parse Server before 8.6.108 and 9.0.0 before 9.10.5-alpha.9

References

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