{ "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": "2026-09-04T12:04:44.445Z" }, "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": [ { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:cluster_observability_operator:1.5::el9" ], "defaultStatus": "affected", "packageName": "cluster-observability-operator/logging-console-plugin-pf4-rhel9", "product": "Cluster Observability Operator 1.5.0", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1782839279", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:cluster_observability_operator:1.5::el9" ], "defaultStatus": "affected", "packageName": "cluster-observability-operator/logging-console-plugin-pf5-rhel9", "product": "Cluster Observability Operator 1.5.0", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1782840539", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:cluster_observability_operator:1.5::el9" ], "defaultStatus": "affected", "packageName": "cluster-observability-operator/troubleshooting-panel-console-plugin-pf6-rhel9", "product": "Cluster Observability Operator 1.5.0", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1782839996", "versionType": "rpm" } ] }, { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:openshift_devspaces:3.27::el9" ], "defaultStatus": "affected", "packageName": "devspaces/code-rhel9", "product": "Red Hat OpenShift Dev Spaces 3.27", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1776744110", "versionType": "rpm" } ] }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:cryostat:4" ], "defaultStatus": "unaffected", "packageName": "handlebars", "product": "Cryostat 4", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/elasticsearch6-rhel9", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/elasticsearch-operator-bundle", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/elasticsearch-proxy-rhel9", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/elasticsearch-rhel9-operator", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/kibana6-rhel8", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:logging:5" ], "defaultStatus": "affected", "packageName": "openshift-logging/logging-curator5-rhel9", "product": "Logging Subsystem for Red Hat OpenShift", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:jboss_data_grid:8" ], "defaultStatus": "unaffected", "packageName": "handlebars", "product": "Red Hat Data Grid 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:10" ], "defaultStatus": "unaffected", "packageName": "firefox", "product": "Red Hat Enterprise Linux 10", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:10" ], "defaultStatus": "unaffected", "packageName": "thunderbird", "product": "Red Hat Enterprise Linux 10", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:7" ], "defaultStatus": "unaffected", "packageName": "firefox", "product": "Red Hat Enterprise Linux 7", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "affected", "packageName": "389-ds:1.4/389-ds-base", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "unaffected", "packageName": "firefox", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "unaffected", "packageName": "grafana", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "affected", "packageName": "mozjs60", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:8" ], "defaultStatus": "unaffected", "packageName": "thunderbird", "product": "Red Hat Enterprise Linux 8", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:9" ], "defaultStatus": "affected", "packageName": "firefox", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/o:redhat:enterprise_linux:9" ], "defaultStatus": "unaffected", "packageName": "thunderbird", "product": "Red Hat Enterprise Linux 9", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:openshift_ai" ], "defaultStatus": "unaffected", "packageName": "rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9", "product": "Red Hat OpenShift AI (RHOAI)", "vendor": "Red Hat" }, { "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": [ "cpe:/a:redhat:jboss_enterprise_bpms_platform:7" ], "defaultStatus": "unaffected", "packageName": "handlebars", "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": "2026-09-04T12:04:44.445Z" } } ] } }