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CVE-2021-20086

CVE-2021-20086: Prototype Pollution in jquery-bbq

8.8

CVSS Score
3.1

Basic Information

CVE ID
CVE-2021-20086
GHSA ID
GHSA-7w8j-85wm-6xfq
EPSS Score
0.62312%
CWE
CWE-1321
Published
5/24/2021
Updated
2/1/2023
KEV Status
No
Technology
TechnologyJavaScript

Technical Details

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Package NameEcosystemVulnerable VersionsFirst Patched Version
jquery-bbqnpm<= 1.2.1

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stems from the $.deparam function's handling of nested parameter keys. The code splits keys using bracket notation (e.g., 'a[b][c]') and recursively builds object structures. When processing keys like 'proto[polluted]' or 'constructor[prototype][polluted]', it improperly assigns values to Object.prototype due to lack of prototype chain validation. The provided PoC and code analysis from BlackFan's repository confirm this vector. The function's role in parsing untrusted URL parameters makes it the clear entry point for prototype pollution.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

WAF Protection Rules

WAF Rule

Improp*rly *ontroll** Mo*i*i**tion o* O*j**t Prototyp* *ttri*ut*s ('Prototyp* Pollution') in jqu*ry-**q *.*.* *llows * m*li*ious us*r to inj**t prop*rti*s into O*j**t.prototyp*.

Reasoning

T** vuln*r**ility st*ms *rom t** $.**p*r*m *un*tion's **n*lin* o* n*st** p*r*m*t*r k*ys. T** *o** splits k*ys usin* *r**k*t not*tion (*.*., '*[*][*]') *n* r**ursiv*ly *uil*s o*j**t stru*tur*s. W**n pro**ssin* k*ys lik* '__proto__[pollut**]' or '*onst