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MEDIUM severity

CVE-2026-2950 lodash

MEDIUM

CVE-2026-2950 is a medium-severity (CVSS 6.5) CWE-1321 vulnerability in lodash. A fix is available for lodash — see the affected versions and patch details below.

lodash vulnerable to Prototype Pollution via array path bypass in `_.unset` and `_.omit`

Published
Mar 31, 2026
Updated
Aug 12, 2026
Affected
4 pkgs
Patched
4 / 4
Exploits
None indexed
Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-2950.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

CVE-2026-2950 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

4 pkgs 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.

198Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
lodashnpm
128.8Mdownloads / week
lodash-esnpm
34.3Mdownloads / week
lodash-amdnpm
10Kdownloads / week

Description

Impact:

Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the _.unset and _.omit functions. The fix for (CVE-2025-13465: https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg) only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as Object.prototype, Number.prototype, and String.prototype.

The issue permits deletion of prototype properties but does not allow overwriting their original behavior.

Patches:

This issue is patched in 4.18.0.

Workarounds:

None. Upgrade to the patched version.

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
📦npmlodashall versions4.18.0npm install lodash@4.18.0
📦npmlodash-esall versions4.18.0npm install lodash-es@4.18.0
📦npmlodash-amdall versions4.18.0npm install lodash-amd@4.18.0
📦npmlodash.unset4.0.0&&< 4.18.04.18.0npm install lodash.unset@4.18.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

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

  2. Fix

    Update lodash to 4.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-2950 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.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-2950 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-2950. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
Red Hat Developer Hub 1.10rhdh/rhdh-hub-rhel9:1780930740RHSA-2026:24841
Red Hat Hardened Imagesnodejs25-main-25.9.0-1.1.hum1RHSA-2026:7378
Red Hat Hardened Imagesyarnpkg-main-1.22.22-18.1.hum1RHSA-2026:7655
Red Hat Hardened Imagesnodejs20-main-20.20.2-1.hum1RHSA-2026:9455
UbuntuMEDIUM

Frequently Asked Questions

Impact: Lodash versions 4.17.23 and earlier are vulnerable to prototype pollution in the _.unset and _.omit functions. The fix for (CVE-2025-13465: https://github.com/lodash/lodash/security/advisories/GHSA-xxjr-mmjv-4gpg) only guards against string key members, so an attacker can bypass the check by passing array-wrapped path segments. This allows deletion of properties from built-in prototypes such as Object.prototype, Number.prototype, and String.prototype. The issue permits deletion of prototype properties but does not allow overwriting their original behavior. Patches: This issue is pa
O3 Security · Impact-Aware SCA

Is CVE-2026-2950 in your dependencies?

O3 Security finds CVE-2026-2950 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

CVE-2026-2950: lodash (Medium 6.5) | O3 Security