CVE-2026-97151
Published:September 24, 2026
Updated:October 13, 2026
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.
Affected Packages
mammoth (CDN_JS):
Affected version(s) >=1.0.0 <1.12.2Fix Suggestion:
Update to version 1.12.2https://github.com/mwilliamson/mammoth.js.git (GITHUB):
Affected version(s) >=1.0.0 <1.12.2Fix Suggestion:
Update to version 1.12.2mammoth (NPM):
Affected version(s) >=1.0.0 <1.12.2Fix Suggestion:
Update to version 1.12.2Related Resources (8)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.4
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
LOW
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
9.4
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
HIGH
Weakness Type (CWE)
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
EPSS
Base Score:
0.36