{"id":"CVE-2026-33940","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, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePart…","severity":"high","cvss":8.1,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-94","CWE-843","CWE-94"],"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-2026-33940","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-xhpv-hc6g-r9c6","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-2026-33940","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2452521","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33940.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}],"tags":["nvd"],"epss":0.00703,"epssPercentile":0.51451,"ingestedAt":"2026-07-02T12:34:40.410Z","slug":"CVE-2026-33940","body":"## Overview\n\nHandlebars 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.\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":45,"depthScoreParts":{"impact":44.6,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}