Description
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePartial()` to return `undefined`. The Handlebars runtime then treats the unresolved partial as a source that needs to be compiled, passing the crafted object to `env.compile()`. Because the object is a valid Handlebars AST containing injected code, the generated JavaScript executes arbitrary commands on the server. The attack requires the adversary to control a value that can be returned by a dynamic partial lookup. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). Without `compile()`, the fallback compilation path in `invokePartial` is unreachable. Second, sanitize context data before rendering: Ensure no value in the context is a non-primitive object that could be passed to a dynamic partial. Third, avoid dynamic partial lookups (`{{> (lookup ...)}}`) when context data is user-controlled.
INFO
Published Date :
2026-03-27T21:11:10.719Z
Last Modified :
2026-04-01T03:55:41.422Z
Source :
GitHub_M
AFFECTED PRODUCTS
The following products are affected by CVE-2026-33940 vulnerability.
| Vendors | Products |
|---|---|
| Handlebarsjs |
|
REFERENCES
Here, you will find a curated list of external links that provide in-depth information to CVE-2026-33940.
