{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33939","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-03-24T19:50:52.103Z","datePublished":"2026-03-27T21:08:24.664Z","dateUpdated":"2026-07-02T12:05:17.067Z"},"containers":{"cna":{"title":"Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation","problemTypes":[{"descriptions":[{"cweId":"CWE-754","lang":"en","description":"CWE-754: Improper Check for Unusual or Exceptional Conditions","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"references":[{"name":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff","tags":["x_refsource_CONFIRM"],"url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff"},{"name":"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2","tags":["x_refsource_MISC"],"url":"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2"},{"name":"https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9","tags":["x_refsource_MISC"],"url":"https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"}],"affected":[{"vendor":"handlebars-lang","product":"handlebars.js","versions":[{"version":">= 4.0.0, < 4.7.9","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-03-27T21:08:24.664Z"},"descriptions":[{"lang":"en","value":"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 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."}],"source":{"advisory":"GHSA-9cx6-37pm-9jff","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-30T18:52:18.558792Z","id":"CVE-2026-33939","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-03-30T18:52:24.142Z"}},{"affected":[{"cpes":["cpe:/a:redhat:cluster_observability_operator:1.5::el9"],"defaultStatus":"affected","product":"Cluster Observability Operator 1.5.0","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:openshift_devspaces:3.27::el9"],"defaultStatus":"affected","product":"Red Hat OpenShift Dev Spaces 3.27","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:logging:5"],"defaultStatus":"affected","product":"Logging Subsystem for Red Hat OpenShift","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:8"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 8","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:9"],"defaultStatus":"affected","product":"Red Hat Enterprise Linux 9","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:cryostat:4"],"defaultStatus":"unaffected","product":"Cryostat 4","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:jboss_data_grid:8"],"defaultStatus":"unaffected","product":"Red Hat Data Grid 8","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:10"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 10","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:7"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 7","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:openshift_ai"],"defaultStatus":"unaffected","product":"Red Hat OpenShift AI (RHOAI)","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:jboss_enterprise_bpms_platform:7"],"defaultStatus":"unaffected","product":"Red Hat Process Automation 7","vendor":"Red Hat"}],"datePublic":"2026-03-27T21:08:24.664Z","descriptions":[{"lang":"en","value":"A flaw was found in Handlebars.js. A remote attacker can exploit this by submitting a malformed Handlebars template that includes decorator syntax referencing an unregistered decorator. When the application attempts to compile this template without proper error handling, it triggers an unhandled `TypeError`. This error causes the Node.js process to crash, resulting in a Denial of Service (DoS) for the affected application."}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-248","description":"Uncaught Exception","lang":"en","type":"CWE"}]}],"references":[{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-33939"},{"name":"RHBZ#2452508","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2452508"},{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33939.json"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:34342"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:10175"}],"solutions":[{"lang":"en","value":"RHSA-2026:34342: Cluster Observability Operator 1.5.0"},{"lang":"en","value":"RHSA-2026:10175: Red Hat OpenShift Dev Spaces 3.27"}],"timeline":[{"lang":"en","time":"2026-03-27T22:01:36.296Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-03-27T21:08:24.664Z","value":"Made public."}],"title":"handlebars.js: Handlebars.js: Denial of Service via malformed decorator syntax in template compilation","workarounds":[{"lang":"en","value":"To mitigate this issue, applications utilizing Handlebars.js should implement robust error handling during template compilation and rendering. Specifically, wrap template compilation and rendering calls in `try/catch` blocks to gracefully handle `TypeError` exceptions. Alternatively, validate user-supplied template input to reject decorator syntax (`{{*...}}`) if decorators are not actively used by the application. Employing a pre-compilation workflow, where templates are compiled at build time and only pre-compiled templates are served, can also prevent runtime exploitation. If the application is a service, a restart may be required for changes to take effect."}],"x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"},"providerMetadata":{"orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","shortName":"redhat-SADP","dateUpdated":"2026-07-02T12:05:17.067Z"}}]}}