CVE-2021-23358 is a high-severity (CVSS 7.2) Code Injection vulnerability in underscore. 4 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for underscore — see the affected versions and patch details below.
Arbitrary Code Execution in underscore
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-23358.
EPSS Exploitation Probability
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
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.
underscorenpmDescription
The package underscore from 1.13.0-0 and before 1.13.0-2, from 1.3.2 and before 1.12.1 are vulnerable to Arbitrary Code Injection via the template function, particularly when a variable property is passed as an argument as it is not sanitized.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | underscore | ≥ 1.3.2&&< 1.12.1 | 1.12.1npm install underscore@1.12.1 |
Affected Products
debian linuxdebianfedorafedoraprojecttenable.sctenableunderscoreunderscorejsResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for underscore, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update underscore to 1.12.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-23358 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
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.
Whilst the OpenShift Container Platform (OCP) openshift4/ose-grafana and openshift3/grafana as well as console, grc-ui and search-ui containers for Red Hat Advanced Management for Kubernetes (RHACM) include the vulnerable underscore library, the access to it is protected by OpenShift OAuth. Additionally this library…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Advanced Cluster Management for Kubernetes 2.0 for RHEL 8 | rhacm2/acm-operator-bundle:v2.0.10-8 | RHSA-2021:1448 |
| Red Hat Ceph Storage 7.1 | ceph-2:18.2.1-381.el8cp | RHSA-2026:2769 |
| Red Hat Virtualization Engine 4.4 | ovirt-engine-ui-extensions-0:1.2.7-1.el8ev | RHSA-2021:2865 |
| Red Hat Virtualization Engine 4.4 | ovirt-web-ui-0:1.9.1-1.el8ev | RHSA-2022:6393 |
| Red Hat Ceph Storage 8 | rhceph/grafana-rhel9:1770630607 | RHSA-2026:2737 |
| Red Hat Ceph Storage 9 | rhceph/grafana-rhel10:1771399331 | RHSA-2026:3406 |
Frequently Asked Questions
Is CVE-2021-23358 in your dependencies?
Find it across npm, including transitive dependencies.