CVE-2026-33941Public exploit

Arbitrary JavaScript execution via unescaped precompiler inputs

Published Mar 27, 2026 · Updated Mar 27, 2026

Code injection in Handlebars.js 4.0.0 through 4.7.8 allows local users to execute arbitrary JavaScript through crafted CLI inputs. The CLI precompiler in bin/handlebars and lib/precompiler.js interpolates template names, namespace values, and module paths into generated source without escaping JavaScript delimiters. Exploitation requires control of a filename or precompiler option and execution of the emitted bundle, after which the injected code runs with the bundle consumer's privileges.

CVSS severity8.2
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Code injection in Handlebars.js 4.0.0 through 4.7.8 allows local users to execute arbitrary JavaScript through crafted CLI inputs. The CLI precompiler in bin/handlebars and lib/precompiler.js interpolates template names, namespace values, and module paths into generated source without escaping JavaScript delimiters. Exploitation requires control of a filename or precompiler option and execution of the emitted bundle, after which the injected code runs with the bundle consumer's privileges.

The record

CVE
CVE-2026-33941
Published
Mar 27, 2026
Updated
Mar 27, 2026
Vendor
Handlebars
Product
Handlebars.js
Classifications
CWE-94, CWE-79, CWE-116, T1059.007
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.0.0, < 4.7.9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Handlebars · Handlebars.jsversion=>= 4.0.0, < 4.7.9

Published CVSS scores

8.2GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
8.2redhat-SADPCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-116Improper Encoding or Escaping of Output
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo