GHSA-v88g-cgmw-v5xw CVE-2020-15366
Prototype Pollution in Ajv
- Severity
- 5.6 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 2.31%
- Chance of exploitation in the next 30 days. Higher than 83.41% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
- CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes
- Fix
6.12.3- Upgrade ajv to this version or later
Description
An issue was discovered in ajv.validate() in Ajv (aka Another JSON Schema Validator) 6.12.2. A carefully crafted JSON schema could be provided that allows execution of other code by prototype pollution. (While untrusted schemas are recommended against, the worst case of an untrusted schema should be a denial of service, not execution of code.)
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| ajv | < 6.12.3 |
6.12.3 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
ajv npm → 6.12.3
- npm
npm install ajv@6.12.3- yarn
yarn add ajv@6.12.3- pnpm
pnpm add ajv@6.12.3
Severity breakdown
CVSS 3.1 5.6
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Weakness
CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
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 to prevent it
- Implementation: By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- Architecture and Design: By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- Implementation: When handling untrusted objects, validating using a schema can be used.
- Implementation: By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
- Implementation: Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes
The product receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified.
How to prevent it
- Implementation: If available, use features of the language or framework that allow specification of allowlists of attributes or fields that are allowed to be modified. If possible, prefer allowlists over denylists. For applications written with Ruby on Rails, use the attr_accessible (allowlist) or attr_protected (denylist) macros in each class that may be used in mass assignment.
- Architecture and Design, Implementation: If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
- Implementation: For any externally-influenced input, check the input against an allowlist of internal object attributes or fields that are allowed to be modified.
- Implementation, Architecture and Design: Refactor the code so that object attributes or fields do not need to be dynamically identified, and only expose getter/setter functionality for the intended attributes.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-2g4f-4pwh-qvx6 ajv has ReDoS when using `$data` option | Medium | Also affects ajv |
| GHSA-6wvx-3r32-xmcg Forge: Prototype Pollution in forge.http cookie handling via a malicious Set-Cookie | Medium | Same weakness, CWE-1321 |
| GHSA-7648-jmwf-vw7j systeminformation has prototype pollution in `networkStats()` via the interface name | Medium | Same weakness, CWE-1321 |
| GHSA-m2m5-rw3w-cwmj ApostropheCMS: Client-side Prototype Pollution in apos.http.parseQuery leading to DOM-based XSS against authenticated users | Medium | Same weakness, CWE-1321 |
| GHSA-j5rq-xfvr-p969 ApostropheCMS: Authenticated projection-exclusion prototype-member deletion in @apostrophecms/db-connect causes process-wide denial of service | High | Same weakness, CWE-1321 |
| GHSA-97rh-rhh2-7vjv Payload: Remote Code Execution through first-register | High | Same weakness, CWE-1321 |
| GHSA-4q55-j62x-fr9h devalue: Malformed null-prototype object keys bypass __proto__ rejection via property-key coercion | Medium | Same weakness, CWE-1321 |
| GHSA-x97p-jq2g-jp4f Axios: Prototype Pollution Gadget in axios toFormData Options | High | Same weakness, CWE-1321 |
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