CVE-2026-97151
Received Received - Intake

Prototype Pollution in Mammoth.js Document Conversion

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: MITRE

Description
mammoth (aka mammoth.js) before 1.12.2 is vulnerable to prototype pollution when reading the styles defined in a document. Converting a crafted .docx file allows an attacker to add arbitrary properties to Object.prototype. In 1.11.0 through 1.12.1, applications that convert further documents in the same process and return the converted HTML can also disclose the contents of local server files (to the party supplying the documents) by setting externalFileAccess to true.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-97151
EUVD
EUVD-2026-85782

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
mammoth.js mammoth From 1.11.0 (inc) to 1.12.1 (inc)
mammoth.js mammoth 1.12.2

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
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.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability is a prototype pollution issue in the mammoth.js library before version 1.12.2. It occurs when processing styles in a .docx file. Attackers can craft documents to add arbitrary properties to Object.prototype, potentially allowing them to manipulate application behavior or access sensitive data.

Detection Guidance

To detect this vulnerability, check if your system uses mammoth.js versions before 1.12.2. Run: npm list mammoth.js or npm list mammoth. If the version is below 1.12.2, the system is vulnerable.

Impact Analysis

If you use mammoth.js versions before 1.12.2, an attacker could exploit this to modify application behavior, access local server files (if externalFileAccess is enabled), or perform other unintended actions by polluting the prototype chain.

Mitigation Strategies

Upgrade mammoth.js to version 1.12.2 or later. If upgrading is not possible, review document processing workflows to avoid using untrusted .docx files. Set externalFileAccess to false if applicable.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-97151. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart