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CRITICAL severity

GHSA-f2jv-r9rf-7988

CRITICALFix: handlebars-lang/handlebars.js@b6d3de7

GHSA-f2jv-r9rf-7988 is a critical-severity (CVSS 9.8) remote code execution vulnerability in org.webjars:handlebars. 4 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-f2jv-r9rf-7988 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Remote code execution in handlebars when compiling templates

Also known asCVE-2021-23369
Published
May 6, 2021
Updated
Feb 4, 2026
Affected
4 pkgs
Patched
4 / 4
Exploits
4 known
Exploitation data as of Feb 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

4 pkgs affected
org.webjars:handlebarsorg.webjars.npm:handlebarsorg.webjars.bowergithub.wycats:handlebars.js📦handlebars

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

The package handlebars before 4.7.7 are vulnerable to Remote Code Execution (RCE) when selecting certain compiling options to compile templates coming from an untrusted source.

Affected Packages

4 total 4 fixed
EcosystemPackageVulnerable rangeFix
Mavenorg.webjars:handlebarsall versions4.7.7
Mavenorg.webjars.npm:handlebarsall versions4.7.7
Mavenorg.webjars.bowergithub.wycats:handlebars.jsall versions4.7.7
📦npmhandlebarsall versions4.7.7
Exploits & PoCs
4

Research 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 dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.webjars:handlebars. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update org.webjars:handlebars to 4.7.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f2jv-r9rf-7988 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 pinpoints whether GHSA-f2jv-r9rf-7988 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-f2jv-r9rf-7988. 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

Red Hat OpenShift Container Platform (OCP) 4 delivers the kibana package which includes Handlebars.js. From OCP 4.6, the kibana package is no longer shipped and will not be fixed. The openshift4/ose-logging-kibana6 container includes Handlebars.js directly as container first code. In OpenShift Container Platform…

Frequently Asked Questions

The package handlebars before 4.7.7 are vulnerable to Remote Code Execution (RCE) when selecting certain compiling options to compile templates coming from an untrusted source.
O3 Security · Impact-Aware SCA

Is GHSA-f2jv-r9rf-7988 in your dependencies?

O3 detects GHSA-f2jv-r9rf-7988 across Maven, npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.