CVE-2026-33941
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.
Statement
Important: This flaw in Handlebars allows arbitrary code execution when the CLI precompiler processes untrusted inputs. An attacker who can influence template filenames or command-line arguments can inject malicious JavaScript, which executes when the generated bundle is loaded. Red Hat products utilizing the Handlebars CLI precompiler in environments where untrusted inputs are processed may be affected.
Mitigation
To mitigate this issue, ensure all inputs to the Handlebars CLI precompiler are thoroughly validated, rejecting characters with JavaScript string-escaping significance (e.g., \" , \' , ;). For automated build pipelines, configure a fixed and trusted namespace string via a configuration file rather than passing it through command-line arguments. Additionally, consider running the precompiler within a sandboxed environment, such as a container with restricted write access, to limit the potential impact of successful exploitation.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | 8.2 | 8.2 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | Required | Required | Required |
| Scope | Changed | Changed | Changed |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
In some cases, injectable code controls authentication; this may lead to a remote vulnerability.
Access Control
Technical Impact: Gain Privileges or Assume Identity
Injected code can access resources that the attacker is directly prevented from accessing.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
When a product allows a user's input to contain code syntax, it might be possible for an attacker to craft the code in such a way that it will alter the intended control flow of the product. As a result, code injection can often result in the execution of arbitrary code. Code injection attacks can also lead to loss of data integrity in nearly all cases, since the control-plane data injected is always incidental to data recall or writing.
Non-Repudiation
Technical Impact: Hide Activities
Often the actions performed by injected control code are unlogged.
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