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Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

CVE-2026-44292

Medium
5.3/10

Summary

protobufjs compiles protobuf definitions into JavaScript (JS) functions. In versions prior to 7.5.6 and 8.x prior to 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.

  • LOW
  • NETWORK
  • LOW
  • UNCHANGED
  • NONE
  • NONE
  • NONE
  • NONE

CWE-1321 - Prototype Pollution

Prototype pollution is one of the lesser-known vulnerabilities. It allows attackers to abuse the rules of JavaScript by injecting properties into the general object “Object” in JS. Modifying the prototype of “Object” affects the behavior of all objects in the entire app, potentially resulting in denial of service, arbitrary code execution, cross-site scripting, etc.

References

Advisory Timeline

  • Published