High 8.3Published Mar 27, 2026

CVE-2026-33941Handlebars.js has JavaScript Injection in CLI Precompiler via Unescaped Names and Options

Updated under an hour ago (Oct 26, 2026, 6:10 PM ET)

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It affects handlebars-lang handlebars.js and 10 other products. Add what you run to find out whether that includes you.

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Every CVE for handlebars-lang handlebars.js

Exploited in the last 30 days

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, the Handlebars CLI precompiler (`bin/handlebars` / `lib/precompiler.js`) concatenates user-controlled strings — template file names and several CLI options — directly into the JavaScript it emits, without any escaping or sanitization. An attacker who can influence template filenames or CLI arguments can inject arbitrary JavaScript that executes when the generated bundle is loaded in Node.js or a browser. Version 4.7.9 fixes the issue. Some workarounds are available. First, validate all CLI inputs before invoking the precompiler. Reject filenames and option values that contain characters with JavaScript string-escaping significance (`"`, `'`, `;`, etc.). Second, use a fixed, trusted namespace string passed via a configuration file rather than command-line arguments in automated pipelines. Third, run the precompiler in a sandboxed environment (container with no write access to sensitive paths) to limit the impact of successful exploitation. Fourth, audit template filenames in any repository or package that is consumed by an automated build pipeline.

CVSS: 8.3 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Weakness (CWE): CWE-79, CWE-94, CWE-116
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Sep 11, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

handlebars-lang handlebars.js handlebars_lang:handlebars.js (from the name)	from 4.0.0, < 4.7.9	CNA record
Red Hat Cluster Observability Operator 1.5.0 redhat:cluster_observability_operator	from 1782839279 not affected	CISA ADP
Red Hat Red Hat OpenShift Dev Spaces 3.27 redhat:openshift_devspaces	from 1776744110 not affected	CISA ADP
Red Hat Cryostat 4 redhat:cryostat	4	CISA ADP
Red Hat Logging Subsystem for Red Hat OpenShift redhat:logging	5	CISA ADP
Red Hat Red Hat Data Grid 8 redhat:jboss_data_grid	8	CISA ADP
Red Hat Red Hat Developer Hub redhat:rhdh	1	CISA ADP
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux	10	CISA ADP
Red Hat Red Hat OpenShift AI (RHOAI) redhat:openshift_ai	Versions not stated	CISA ADP
Red Hat Red Hat Process Automation 7 redhat:jboss_enterprise_bpms_platform	7	CISA ADP
1–10 of 11

References

References

https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf	x-refsource-confirm, exploit, vendor-advisory
https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2	x-refsource-misc, patch
https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9	x-refsource-misc, release-notes
https://access.redhat.com/errata/RHSA-2026:10175
https://access.redhat.com/errata/RHSA-2026:34342
https://access.redhat.com/security/cve/CVE-2026-33941
https://bugzilla.redhat.com/show_bug.cgi?id=2452524
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33941.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.