CVE-2021-23518

The package cached-path-relative before 1.1.0 are vulnerable to Prototype Pollution via the cache variable that is set as {} instead of Object.create(null) in the cachedPathRelative function, which allows access to the parent prototype properties when the object is used to create the cached relative path. When using the origin path as proto, the attribute of the object is accessed instead of a path. Note: This vulnerability derives from an incomplete fix in https://security.snyk.io/vuln/SNYK-JS-CACHEDPATHRELATIVE-72573

Weakness

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

Affected Software

Extended Description

By adding or modifying attributes of an object prototype, it is possible to create attributes that exist on every object, or replace critical attributes with malicious ones. This can be problematic if the product depends on existence or non-existence of certain attributes, or uses pre-defined attributes of object prototype (such as hasOwnProperty, toString or valueOf). This weakness is usually exploited by using a special attribute of objects called proto, constructor or prototype. Such attributes give access to the object prototype. This weakness is often found in code that assigns object attributes based on user input, or merges or clones objects recursively.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/180.html
• https://cwe.mitre.org/data/definitions/77.html

References

• https://github.com/ashaffer/cached-path-relative/commit/40c73bf70c58add5aec7d11e4f36b93d144bb760
• https://lists.debian.org/debian-lts-announce/2022/12/msg00006.html
• https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-2348246
• https://snyk.io/vuln/SNYK-JS-CACHEDPATHRELATIVE-2342653