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Vulnerabilities

Vulnerability · CVE-2026-33939

Handlebars provides the power necessary to let users build semantic templates.

Published Mar 27, 2026 · catalog updated Sep 4, 2026 · Handlebars provides the power

Check if you run it

No confirmed exploitation is on record for CVE-2026-33939. EPSS is 0.76%. Act only if a listed version of Handlebars provides the power is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Handlebars provides the power).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.76%
Remediation
Advisory link
Affected products
cpe handlebarsjs/handlebars

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe handlebarsjs/handlebarsversion unspecified

How to fix CVE-2026-33939

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-33939. EPSS is 0.76%. Act only if a listed version of Handlebars provides the power is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-248; CWE-754. EPSS 0.76%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. 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

  2. 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

Sources

  • CVE.orgVulnerability recordCVE-2026-33939

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-33939

    30-day exploitation probability 0.8%

    first.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

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.