CVE-2026-33941

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 8.3 / 10
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Effective score: 8.3 / 10 HIGH source: CNA overview
MSRC score: 8.2 / 10 HIGH MS rating: Important
CWE(s): CWE-79, CWE-94, CWE-116
Reserved: 2026-03-24
Published: 2026-03-27 22:13 UTC
Last updated: 2026-04-01 05:55 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33941.json
Linked Threat: CVE-2026-33941 — Handlebars.js has JavaScript Injection in CLI Precompiler via Unescaped Names and Options

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-03-27 22:16:21 UTC
NVD last modified: 2026-03-31 17:53:18 UTC
NVD CVSS v3.1: 8.2 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Exploitability subscore: 1.5 / 10
Impact subscore: 6.0 / 10
EPSS score: 0.0001 (probability of exploitation in next 30 days)
EPSS percentile: 0.92% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-16862
Assigner: GitHub_M
Published: Mar 27, 2026, 9:13:15 PM
Updated: Apr 1, 2026, 3:55:37 AM
EUVD base score (CVSS 3.1): 8.3 / 10
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
EUVD-reported EPSS: 0.0100
Vendors: handlebars-lang
Products: handlebars.js (4.0.0, < 4.7.9)
Aliases: GHSA-xjpj-3mr7-gcpf

ENISA 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.

EUVD references (3)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-08-12 01:05 UTC (source: CVRF).

MS severity: Important
MS CVSS base score: 8.2 / 10 (temporal 8.2)
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Release: 2026-Mar

Affected products (1)

Vendor	Product	Versions	Platforms
handlebars-lang	handlebars.js	`>= 4.0.0, < 4.7.9` (affected)	—

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:*

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf x_refsource_CONFIRM
https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 x_refsource_MISC
https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9 x_refsource_MISC

Web references (1)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

MSRC update guide: CVE-2026-33941 msrc

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 security-advisories@github.com Patch
https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9 security-advisories@github.com Release Notes
https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf security-advisories@github.com ExploitVendor Advisory

Indicators (3)

IOCs linked to the auto-promoted Threat row.

Type	Value	VirusTotal	Attached
domain	`node.js`	no local data	2026-05-18 21:18 UTC
domain	`handlebars.js`	no local data	2026-05-18 21:18 UTC
domain	`precompiler.js`	no local data	2026-05-18 21:18 UTC

Remediations (13)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Microsoft Issues Second Biggest Patch Tuesday Ever in April

web:redmondmag.com

Microsoft April 2026 Patch Tuesday fixed 163 CVEs , marking its second-largest security update. Three zero-day vulnerabilities impacted SharePoint, Chromium-based Edge workflows and Microsoft Defender.

2026-05-22 16:53 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-22 16:53 UTC
Microsoft Patch Tuesday April 2026 - 168 Vulnerabilities Fixed ...

web:cybersecuritynews.com

Microsoft has released its April 2026 Patch Tuesday security update, addressing 168 vulnerabilities across its product portfolio including one actively exploited zero-day and one publicly disclosed flaw that organizations must prioritize immediately.

2026-05-22 16:53 UTC
Security Update Guide - Loading - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-22 03:59 UTC
Microsoft Patch Tuesday Fixes Notepad Markdown RCE CVE-2026-20841

web:windowsforum.com

Microsoft published the advisory and shipped a fix through Patch Tuesday — that's the canonical remediation channel for Windows customers and enterprises. The availability of a vendor fix , with tracking via CVE and aggregator records, lets defenders plan and execute updates.

2026-05-22 03:59 UTC
Microsoft April 2026 Patch Tuesday fixes 167 flaws, 2 zero-days

web:www.bleepingcomputer.com

Today is Microsoft's April 2026 Patch Tuesday with security updates for 167 flaws, including 2 zero-day vulnerabilities.

2026-05-22 03:59 UTC
Critical Patches Issued for Microsoft Products, April 14, 2026

web:www.cisecurity.org

<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

2026-05-22 03:59 UTC
April 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft's April 2026 Patch Tuesday addresses 164 CVEs , featuring 8 Critical vulnerabilities, one exploited zero-day, and one disclosed zero-day.

2026-05-22 03:59 UTC
Microsoft fixes 167 security flaws in April, second biggest Patch ...

web:www.pcworld.com

This month's Patch Tuesday includes an actively exploited Office zero-day vulnerability and several critical RCE bugs in Windows and Remote Desktop.

2026-05-22 03:59 UTC
Microsoft Issues Massive Windows Patch for 160+ Bugs ... - TechRepublic

web:www.techrepublic.com

Microsoft's April 2026 Patch Tuesday fixes 165 vulnerabilities, including two zero-days, in one of the company's largest monthly security updates.

2026-05-22 03:59 UTC
Patch Tuesday May 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-05-22 03:59 UTC
Microsoft Patch Tuesday May 2026 - 120 Vulnerabilities Fixed, Including ...

web:cybersecuritynews.com

Microsoft's May 2026 Patch Tuesday lands with a heavy enterprise focus, fixing 120 vulnerabilities across Windows, Office, Azure, developer tools, and Microsoft 365 apps, including 29 remote code execution (RCE) flaws rated Critical.

2026-05-22 03:59 UTC
Patch Tuesday, April 2026 Edition - Krebs on Security

web:krebsonsecurity.com

For a clickable, per- patch breakdown, check out the SANS Internet Storm Center Patch Tuesday roundup. Running into problems applying any of these updates?

2026-05-22 03:59 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-33941.json.

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