CVE-2026-33939
Handlebars provides the power necessary to let users build semantic templates.
Published Mar 27, 2026 · corrected/updated Sep 4, 2026 · handlebarsjs handlebars · evidence confidence medium
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. ), the compiled template calls , which returns . The runtime then immediately invokes the result as a function, causing an unhandled that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a is vulnerable to a single-request Denial of Service. Version 4.7.9 fixes the issue. Some workarounds are available. Wrap compilation and rendering in . Validate template input before passing it to ; reject templates containing decorator syntax ( ) if decorators are not used in your application. Use the pre-compilation workflow; compile templates at build time and serve only pre-compiled templates; do not call at request time.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2026-33939 is a high public vulnerability record for handlebarsjs handlebars. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether handlebarsjs handlebars is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: handlebarsjs/handlebars. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 7.5. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-248, CWE-754. Sources contributing to this record: cve_org, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Mar 27, 2026 · NIST NVD
Detected
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. ), the compiled template calls , which returns . The runtime then immediately invokes the result as a function, causing an unhandled that crashes the Node.js process. Any application that com
Sep 4, 2026 · NIST NVD
Updated
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. ), the compiled template calls , which returns . The runtime then immediately invokes the result as a function, causing an unhandled that crashes the Node.js process. Any application that com
Affected
- cpe handlebarsjs/handlebarsversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-33939
Official CVE identifier
cve.org - NIST NVDVulnerability recordCVE-2026-33939
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. ), the compiled template calls `lookupProperty(decorators, "n")
nvd.nist.gov