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CRITICAL severity

CVE-2020-7707 — property-expr

CRITICALFix: jquense/expr@df84691

CVE-2020-7707 is a critical-severity (CVSS 9.8) CWE-1321 vulnerability in property-expr. 2 public exploit references exist, so weaponization risk is real. A fix is available for property-expr — see the affected versions and patch details below.

Prototype Pollution in property-expr

Also known asGHSA-6fw4-hr69-g3rv
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
2 known
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
3.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs88th percentile — riskier than 88% of all scored CVEsHighest risk
1.59%2.35%3.11%3.88%2.1%3.4%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2020-7707 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.

65other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
property-exprnpm
11.1Mdownloads / week

Description

The package property-expr before 2.0.3 are vulnerable to Prototype Pollution via the setter function.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmproperty-exprall versions2.0.3npm install property-expr@2.0.3

Affected Products

1 product · 1 configurations
Application
property-exprproperty-expr_project
< 2.0.3
range
Exploits & PoCs
2

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

The package property-expr before 2.0.3 are vulnerable to Prototype Pollu…

snyk.ioNVDDec 2022

The package property-expr before 2.0.3 are vulnerable to Prototype Pollu…

snyk.ioNVDDec 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update property-expr to 2.0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-7707 is resolved across your whole dependency graph.

  3. Workarounds

    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

The package property-expr before 2.0.3 are vulnerable to Prototype Pollution via the setter function.
O3 Security · Impact-Aware SCA

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CVE-2020-7707: property-expr — Fixed in 2.0.3