CVE-2026-33941

Medium

Elevated severity or exploit probability.

CVSS base

8.2 HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

EPSS — probability of exploitation (30 days)

0.3%

21.9th percentile

CISA KEV

Not listed

Weakness / dates

CWE-94

Published 2026-03-27 · modified 2026-09-04

CVSS breakdown

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Attack Vector	L	Local
Attack Complexity	L	Low
Privileges Required	L	Low
User Interaction	R	Required
Scope	C	Changed
Confidentiality	H	High
Integrity	H	High
Availability	H	High

Timeline

2026-03-27 — Published (NVD)
2026-09-04 — Last modified (NVD)

Description

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.

Affected

handlebarsjs

References

Official: NVD · CVE.org