{"id":"CVE-2026-33939","title":"Handlebars provides the power necessary to let users build semantic templates","summary":"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. `{{*n}}`), the compiled temp…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-754","CWE-248"],"vendor":"handlebarsjs","product":"handlebars","affected":["handlebars >= 4.0.0, < 4.7.9"],"patched":["handlebars 4.7.9"],"published":"2026-03-27","updated":"2026-07-02","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-33939","references":[{"url":"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2","label":"security-advisories@github.com"},{"url":"https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9","label":"security-advisories@github.com"},{"url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff","label":"security-advisories@github.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:10175","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:34342","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/security/cve/CVE-2026-33939","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2452508","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33939.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}],"tags":["nvd"],"epss":0.00616,"epssPercentile":0.48146,"ingestedAt":"2026-07-02T12:34:40.408Z","slug":"CVE-2026-33939","body":"## Overview\n\nHandlebars 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. `{{*n}}`), the compiled template calls `lookupProperty(decorators, \"n\")`, which returns `undefined`. The runtime then immediately invokes the result as a function, causing an unhandled `TypeError: ... is not a function` that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a `try/catch` 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 `try/catch`. Validate template input before passing it to `compile()`; 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 `compile()` at request time.\n\n## Affected\n\n- `handlebars >= 4.0.0, < 4.7.9`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `handlebars 4.7.9`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}