HighCVE-2026-33941

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

Published 27.03.2026Last modified 26.10.2026Sources: Red Hat, BSI, CVE.org, Msrc Update Guide, OSV

Public exploit

What is affected, what to do

An exploit is publicly available. Update handlebars to version 4.7.9, App Connect Enterprise Certified Container to version 13.0.0, InfoSphere Data Replication to version 12.1.5.0-43.

Affected: Handlebars-lang Handlebars.js gte 4.0.0, < 4.7.9..*

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Metrics

8.2

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

8.2

CVSS v3

Severity High on the scale from 0 to 10.

Source: Red Hat, BSI, CVE.org, Msrc Update Guide, OSV

0.3 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 22.1

Show all metrics

Severity: High
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 60.56 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: PoC (publicly reported)
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 8.2 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 8.2
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.3 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 22.1; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 27.03.2026
CWE CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect. Read in glossary: CWE-79, CWE-94, CWE-116, CWE-94

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

A flaw was found in Handlebars. The Handlebars command-line interface (CLI) precompiler concatenates user-controlled strings, such as template file names and CLI options, directly into the generated JavaScript without proper escaping or sanitization. An attacker capable of influencing these inputs can inject arbitrary JavaScript code. This can lead to arbitrary code execution when the generated JavaScript bundle is loaded in a Node.js environment or a web browser.

Source: redhat_csaf, BSI CSAF, BSI WID Portal, NVD (NIST), Microsoft Security Update Guide, OSV (Open Source Vulnerabilities), CVE.org (MITRE), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
handlebars-lang	handlebars.js	`≥ 4.0.0, < 4.7.9`	—
handlebarsjs	handlebars	`4.0.0 – < 4.7.9`	`4.7.9`
IBM	App Connect Enterprise	`Certified Container <12.0 LTS`	—
IBM	App Connect Enterprise Certified Container	`< 13.0.0`	`13.0.0`
IBM	InfoSphere Data Replication	`< 12.1.5.0-43`	`12.1.5.0-43`
Oracle	REST Data Services	`24.2.0-26.1.0` `24.2.0-26.2.2` `24.2.0-26.2.1`	— — —

Vendors and products

Weakness classes (CWE)

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Base
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Entry at MITRE CWE-79
CWE-94Improper Control of Generation of Code ('Code Injection')
Base
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Entry at MITRE CWE-94
CWE-116Improper Encoding or Escaping of Output
Class
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
Entry at MITRE CWE-116
CWE-94Improper Control of Generation of Code ('Code Injection')
Base
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
Entry at MITRE CWE-94

Public exploit references

Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

Public exploit references

Reference tagged as exploit	github.com (opens in a new tab)	PoC (publicly reported)reported, not verified	—

References & sources

github.comhandlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr…web, x_refsource_CONFIRM, Exploit, Vendor advisory
NVD (NIST)vuln/detail/CVE-2026-33941advisory
github.comhandlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c…web, x_refsource_MISC, Patch
github.comhandlebars-lang/handlebars.jspackage
github.comhandlebars-lang/handlebars.js/releases/tag/v4.7.9web, x_refsource_MISC, Release notes
access.redhat.comsecurity/cve/CVE-2026-33941Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2452524Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-33941.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:34342Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:10175Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

01.09.2026Record modifiedGitHub

New references:

Show 9 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
Reference	added	—	https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
Reference	added	—	https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf
Reference	removed	https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2	—
Reference	removed	https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9	—
Reference	removed	https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf	—
Reference type	removed	https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 Types: Patch	—
Reference type	removed	https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9 Types: Release Notes	—
Reference type	removed	https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xjpj-3mr7-gcpf Types: Exploit, Vendor Advisory	—

Source identifier: security-advisories@github.com

01.09.2026Record modifiedRed Hat ADP

New references:

and 1 more reference

Show 11 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/33xxx/CVE-2026-33941.json">CVE-2026-33941</a>
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:10175
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:34342
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-33941
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2452524
Reference	added	—	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33941.json
Reference	removed	https://access.redhat.com/errata/RHSA-2026:10175	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:34342	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-33941	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2452524	—
Reference	removed	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33941.json	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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