protobuf.js: Code generation gadget after prototype pollution
Platform
nodejs
Component
protobufjs
Summary
protobufjs used plain objects with inherited prototypes for internal type lookup tables used by generated encode and decode functions. If Object.prototype had already been polluted, those lookup tables could resolve attacker-controlled inherited properties as valid protobuf type information.
This could cause attacker-controlled strings to be emitted into generated JavaScript code.
Impact
An attacker who can first trigger a prototype pollution vulnerability may be able to influence generated protobufjs encode or decode functions in a way that can lead to arbitrary JavaScript execution.
This issue requires a separate prototype pollution primitive before protobufjs is invoked.
Applications without a reachable prototype pollution primitive are not directly exploitable through this issue alone.
Preconditions
- The application or one of its dependencies must allow an attacker to pollute
Object.prototype. - The polluted property must affect protobufjs internal type lookup behavior.
- The application must use protobufjs functionality that generates encode or decode code for affected types.
- The generated code path must be reached after the prototype pollution has occurred.
Workarounds
Avoid running affected versions in applications where attacker-controlled input can pollute Object.prototype. If immediate upgrade is not possible, remove or mitigate reachable prototype pollution primitives and isolate schema/message processing from untrusted application state.
Threat Intelligence
Exploit Status
CVSS Vector
What do these metrics mean?
- Attack Vector
- Network — remotely exploitable over the internet. No physical or local access required. Widest attack surface.
- Attack Complexity
- High — requires a race condition, non-default configuration, or specific circumstances. Harder to exploit reliably.
- Privileges Required
- None — unauthenticated. No login or credentials needed to exploit.
- User Interaction
- None — attack is automatic and silent. Victim does nothing: no click, no file open.
- Scope
- Unchanged — impact is limited to the vulnerable component itself.
- Confidentiality
- High — complete confidentiality loss. Attacker can read all data: credentials, keys, personal data.
- Integrity
- High — attacker can write, modify, or delete any data: databases, config files, or code.
- Availability
- High — complete crash or resource exhaustion. Full denial of service.
Affected Software
Weakness Classification (CWE)
Timeline
- Published
How to fix
No official patch available. Check for workarounds or monitor for updates.
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