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HIGH severity

CVE-2025-3197 — expand-object

HIGH

CVE-2025-3197 is a high-severity (CVSS 7.3) CWE-1321 vulnerability in expand-object. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

expand-object Vulnerable to Prototype Pollution via the expand() Function

Published
Updated
Affected
1 pkg
Patched
None yet
Exploits
None indexed
Exploitation data as of Oct 20, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-3197.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs34th percentile — riskier than 34% of all scored CVEsHighest risk
0.00%0.36%0.72%1.08%0.6%0.4%Apr 26Aug 26Oct 26

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

How urgent is this, really

Where this sits among everything scored

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.

5other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
expand-objectnpm
12Kdownloads / week

Description

Versions of the package expand-object from 0.0.0 to 0.4.2 are vulnerable to Prototype Pollution in the expand() function in index.js. This function expands the given string into an object and allows a nested property to be set without checking the provided keys for sensitive properties like proto.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmexpand-objectall versionsNo fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Remediation status

    The records we use list no patched version of expand-object for CVE-2025-3197. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  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

Versions of the package expand-object from 0.0.0 to 0.4.2 are vulnerable to Prototype Pollution in the expand() function in index.js. This function expands the given string into an object and allows a nested property to be set without checking the provided keys for sensitive properties like __proto__.
O3 Security · Impact-Aware SCA

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CVE-2025-3197: expand-object (High 7.3)