{"id":"CVE-2026-33938","revision":"afcc36da4f254911880798122d63b4fd","records":[{"revision":"afcc36da4f254911880798122d63b4fd","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-33938","aliases":[],"title":"Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block","description":"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  should treat context data as read-only. Third, avoid registering helpers from third-party packages (such as `handlebars-helpers`) in  contexts where templates or context data can be influenced by untrusted input.","state":0,"publishedAt":"2026-03-27T21:05:42.485+00:00","modifiedAt":"2026-09-04T12:04:55.157+00:00","affected":[{"ecosystem":"Vendor product","name":"handlebars.js","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"handlebars-lang\",\n                    \"product\": \"handlebars.js\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 4.0.0, < 4.7.9\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.1,"severity":"HIGH"}],"references":["https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-3mfm-83xf-c92r","https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2","https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-33938","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-33938","identifiers":["CVE-2026-33938"]},"retained":false,"historicalAffected":[]}],"coverage":[]}