CVE-2026-44292: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in protobufjs protobuf.js
protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance. This vulnerability is fixed in 7.5.6 and 8.0.2.
AI Analysis
Technical Summary
The protobuf.js library, used to compile protobuf definitions into JavaScript functions, improperly handles the __proto__ property when generating message constructors. Specifically, in versions before 7.5.6 and between 8.0.0 and 8.0.2, the library copies enumerable properties from a user-provided object without filtering the __proto__ key. This allows an attacker who can supply a crafted object to alter the prototype of the message instance, leading to prototype pollution. This vulnerability is identified as CWE-1321 and is fixed in protobuf.js versions 7.5.6 and 8.0.2.
Potential Impact
An attacker able to supply a crafted object to protobuf.js message constructors can modify the prototype of that message instance, potentially causing unexpected behavior or integrity issues in the affected application. There is no direct confidentiality or availability impact reported. No known exploits in the wild have been documented.
Mitigation Recommendations
Upgrade protobuf.js to version 7.5.6 or later, or to version 8.0.2 or later, where this prototype pollution vulnerability is fixed. Since the vulnerability is resolved in these versions, applying the official fix is the recommended remediation. Patch status is confirmed by the vendor advisory indicating the fix in these versions.
CVE-2026-44292: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in protobufjs protobuf.js
Description
protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs generated message constructors copied enumerable properties from a provided properties object without filtering the __proto__ key. If an application constructed a message from an attacker-controlled plain object, an own enumerable __proto__ property could alter the prototype of that individual message instance. This vulnerability is fixed in 7.5.6 and 8.0.2.
CVSS v3.1
Score 5.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The protobuf.js library, used to compile protobuf definitions into JavaScript functions, improperly handles the __proto__ property when generating message constructors. Specifically, in versions before 7.5.6 and between 8.0.0 and 8.0.2, the library copies enumerable properties from a user-provided object without filtering the __proto__ key. This allows an attacker who can supply a crafted object to alter the prototype of the message instance, leading to prototype pollution. This vulnerability is identified as CWE-1321 and is fixed in protobuf.js versions 7.5.6 and 8.0.2.
Potential Impact
An attacker able to supply a crafted object to protobuf.js message constructors can modify the prototype of that message instance, potentially causing unexpected behavior or integrity issues in the affected application. There is no direct confidentiality or availability impact reported. No known exploits in the wild have been documented.
Mitigation Recommendations
Upgrade protobuf.js to version 7.5.6 or later, or to version 8.0.2 or later, where this prototype pollution vulnerability is fixed. Since the vulnerability is resolved in these versions, applying the official fix is the recommended remediation. Patch status is confirmed by the vendor advisory indicating the fix in these versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-05T17:39:31.112Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a049721cbff5d8610e00ec6
Added to database: 05/13/2026, 15:22:09 UTC
Last enriched: 05/20/2026, 18:26:18 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 70
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