Automattic Mongoose up to 6.13.11/7.8.12/8.24.6/9.11.3 Merge Clone init/findOneAndReplace/Query.prototype.merge path/value prototype pollution

Summaryinfo

A vulnerability identified as critical has been detected in Automattic Mongoose up to 6.13.11/7.8.12/8.24.6/9.11.3. This affects the function init/findOneAndReplace/Query.prototype.merge of the component Merge Clone. This manipulation of the argument path/value causes prototype pollution. This vulnerability is registered as CVE-2026-125117. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability has been found in Automattic Mongoose up to 6.13.11/7.8.12/8.24.6/9.11.3 and classified as critical. Affected by this vulnerability is the function init/findOneAndReplace/Query.prototype.merge of the component Merge Clone. The manipulation of the argument path/value with an unknown input leads to a prototype pollution vulnerability. The CWE definition for the vulnerability is CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment. Prior to 6.13.12, 7.8.13, 8.24.7, and 9.11.4, Mongoose can descend into inherited properties while loading database documents in init(), setting dotted paths in $__set, and merging update documents in utils.mergeClone. Attacker-controlled keys such as toString or valueOf can therefore cause Mongoose to write into shared built-in functions instead of an own property. A crafted document, Mixed path, non-strict document or subdocument, findOneAndReplace() replacement, chained update, or Query.prototype.merge() source can overwrite Object.prototype.toString.call, causing later queries on unrelated models to fail until the process restarts. Separately, when an attacker controls the dotted path passed to doc.set(path, value) for a subdocument configured with strict: false, descent through $__set can reach $__schema and alter shared validators or schema options for later documents. Mongoose already blocks __proto__, constructor, and prototype, so this issue overwrites properties on reachable shared objects rather than adding new properties directly to Object.prototype. This issue is fixed in versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-125117 since 11/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

Upgrading to version 6.13.12, 7.8.13, 8.24.7 or 9.11.4 eliminates this vulnerability.

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Productinfo

Vendor

• Automattic

Name

• Mongoose

Version

• 6.13.0
• 6.13.1
• 6.13.2
• 6.13.3
• 6.13.4
• 6.13.5
• 6.13.6
• 6.13.7
• 6.13.8
• 6.13.9
• 6.13.10
• 6.13.11
• 7.8.0
• 7.8.1
• 7.8.2
• 7.8.3
• 7.8.4
• 7.8.5
• 7.8.6
• 7.8.7
• 7.8.8
• 7.8.9
• 7.8.10
• 7.8.11
• 7.8.12
• 8.24.0
• 8.24.1
• 8.24.2
• 8.24.3
• 8.24.4
• 8.24.5
• 8.24.6
• 9.11.0
• 9.11.1
• 9.11.2
• 9.11.3

Website

• Product: https://github.com/Automattic/mongoose/

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