cvedb.io
CVE-2026-33938
HIGH · CVSS 8.1
EPSS exploitation probability: 0%
Published 2026-03-27T21:17:27.587 · Last modified 2026-07-02T12:17:08.663

Summary

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

Affected products

handlebarsjs — handlebars

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.