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HIGH severity

CVE-2021-20085 — backbone-query-parameters

HIGH

CVE-2021-20085 is a high-severity (CVSS 8.8) CWE-1321 vulnerability in backbone-query-parameters. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Prototype Pollution in backbone-query-parameters

Also known asGHSA-8qpm-5c82-rf96
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.6%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs75th percentile — riskier than 75% of all scored CVEsHighest risk
0.05%0.73%1.42%2.11%0.5%1.6%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-20085 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
backbone-query-parametersnpm
320downloads / week

Description

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in backbone-query-parameters 0.4.0 allows a malicious user to inject properties into Object.prototype.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmbackbone-query-parametersall versionsNo fix

Affected Products

1 product · 1 configurations
Application
backbone-query-parametersbackbone-query-parameters_project
1 version
0.4.0
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Improperly Controlled Modification of Object Prototype Attributes ('Prot…

github.comNVDApr 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for backbone-query-parameters, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of backbone-query-parameters has shipped for CVE-2021-20085 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in backbone-query-parameters 0.4.0 allows a malicious user to inject properties into Object.prototype.
O3 Security · Impact-Aware SCA

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CVE-2021-20085: backbone-query-parameters (High 8.8)