json5: Improperly Controlled Modification of Object Prototype Attributes
CVE-2022-46175 is a high-severity improperly controlled modification of object prototype attributes vulnerability in json5, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected json5 versions: < 2.2.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 9.7% chance of exploitation within 30 days, which is in the top 4.42% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of json5 you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Json5 | json5 | < 2.2.2 | Not stated |
| Fedora Project | Fedora | 37 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.1 | High | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
JSON5 is an extension to the popular JSON file format that aims to be easier to write and maintain by hand (e.g. for config files). The `parse` method of the JSON5 library before and including versions 1.0.1 and 2.2.1 does not restrict parsing of keys named `__proto__`, allowing specially crafted strings to pollute the prototype of the resulting object. This vulnerability pollutes the prototype of the object returned by `JSON5.parse` and not the global Object prototype, which is the commonly understood definition of Prototype Pollution. However, polluting the prototype of a single object can have significant security impact for an application if the object is later used in trusted operations. This vulnerability could allow an attacker to set arbitrary and unexpected keys on the object returned from `JSON5.parse`. The actual impact will depend on how applications utilize the returned object and how they filter unwanted keys, but could include denial of service, cross-site scripting, elevation of privilege, and in extreme cases, remote code execution. `JSON5.parse` should restrict parsing of `__proto__` keys when parsing JSON strings to objects. As a point of reference, the `JSON.parse` method included in JavaScript ignores `__proto__` keys. Simply changing `JSON5.parse` to `JSON.parse` in the examples above mitigates this vulnerability. This vulnerability is patched in json5 versions 1.0.2, 2.2.2, and later.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes
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.
How developers prevent this class of flaw
- By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- When handling untrusted objects, validating using a schema can be used.
More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/json5/json5/security/advisories/GHSA-9c47-m6qq-7p4hExploit, Third Party Advisory
Patches and release notes
- github.com/json5/json5/issues/199Issue Tracking, Third Party Advisory
- github.com/json5/json5/pull/298Third Party Advisory
Third-party and government advisories
- github.com/json5/json5/issues/295Issue Tracking, Third Party Advisory
Other references
Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
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