VulnerabilityPublished 9 Nov 2026

CVE-2026-125118: Automattic mongoose · Prototype Pollution

Affects Automattic mongooseSource CVE Database V5

Compare

Not known to be exploited · CVSS 6.5 Medium · fixed in 9.11.4 : update Automattic mongoose when convenient.

Data as of 9 Nov 2026, 22:49 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	6.5

Patch: Available – fixed in 9.11.4, 8.24.7, 7.8.13 +1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Automattic mongoose to 9.11.4, 8.24.7, 7.8.13 or 6.13.12.

Affected software

Product	Affected	Fixed in
Automatticmongoose	Affected >=9.0.0 <9.11.4	Fixed in 9.11.4
Automatticmongoose	Affected >=8.0.0 <8.24.7	Fixed in 8.24.7
Automatticmongoose	Affected >=7.0.0 <7.8.13	Fixed in 7.8.13
Automatticmongoose	Affected <6.13.12	Fixed in 6.13.12

AI-suggested

This vulnerability is fixed in mongoose versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4. Users should upgrade to one of these versions or later to remediate the issue. No other mitigation or temporary workaround is indicated.

Description

A prototype pollution vulnerability exists in Automattic's mongoose library prior to versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4. The issue arises because Schema.prototype.virtual() does not apply special-property validation, allowing attackers who control virtual field names to inject properties like __proto__, constructor, or prototype. This can lead to prototype pollution, enabling spoofing of inherited property checks and potentially affecting server-side JavaScript code behavior. The vulnerability has a CVSS score of 6.5 and is classified as medium severity. Fixed versions are available.

Impact

The vulnerability allows attackers to perform prototype pollution by injecting properties into Object.prototype or Function.prototype. This can lead to spoofing of inherited property checks such as authorization flags and manipulation of server-side JavaScript code behavior. The CVSS score of 6.5 indicates a medium severity impact with no confidentiality loss but integrity and availability impacts possible.

Summary

Mongoose, a MongoDB object modeling tool, had a prototype pollution vulnerability in its Schema.prototype.virtual() method before versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4. The method builds nested virtual paths without validating special property names, allowing an attacker who can influence virtual field names in dynamic schemas or schema-as-code systems to supply path segments such as __proto__, constructor, or prototype. This causes the virtual-path reducer to write enumerable properties to Object.prototype or Function.prototype, resulting in prototype pollution. This flaw can spoof inherited property checks like authorization flags and provide function-prototype gadget state to other server-side JavaScript code. The vulnerability is fixed in the stated versions.

CWE-1321Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (opens in a new tab)
Variant weakness
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.
Implementation
By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
Architecture and Design
By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
Implementation · Input Validation
When handling untrusted objects, validating using a schema can be used.
OWASP Cheat Sheets
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.1.2 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Exploiting Incorrectly Configured Access Control Security Levels (opens in a new tab)
Manipulating User-Controlled Variables (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Nov 2026, 22:49 UTC

WeaknessesCWE-1321

Technical details

References

Community reviews

Related threats