Description (CNA)
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, the `@partial-block` special variable is stored in the template data context and is reachable and mutable from within a template via helpers that accept arbitrary objects. When a helper overwrites `@partial-block` with a crafted Handlebars AST, a subsequent invocation of `{{> @partial-block}}` compiles and executes that AST, enabling arbitrary JavaScript execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). The `compile()` method is absent, eliminating the vulnerable fallback path. Second, audit registered helpers for any that write arbitrary values to context objects. Helpers should treat context data as read-only. Third, avoid registering helpers from third-party packages (such as `handlebars-helpers`) in contexts where templates or context data can be influenced by untrusted input.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| handlebars-lang / handlebars.js | affected >= 4.0.0, < 4.7.9 |
CWE
CWE-94, CWE-843
References
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-3mfm-83xf-c92r
- https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
ADP enrichment
No English description supplied.
A flaw was found in Handlebars. A remote attacker can exploit this vulnerability by manipulating the `@partial-block` special variable within the template data context. By overwriting `@partial-block` with a specially crafted Abstract Syntax Tree (AST) through a helper, a subsequent invocation of `{{> @partial-block}}` will compile and execute the malicious AST. This enables arbitrary JavaScript execution on the server, leading to potential compromise of the system.