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

CVE-2025-57820

High
7.9/10

Summary

Svelte devalue is a utility library. In versions 4.0.0 through 5.3.1, a string passed to "devalue.parse" could represent an object with a "__proto__" property, and "devalue.parse" does not check that an index is numeric. This could result in assigning prototypes to objects and properties, leading to Prototype Pollution.

  • LOW
  • NETWORK
  • 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