{"id":"CVE-2026-33940","sourceIdentifier":"security-advisories@github.com","published":"2026-03-27T22:16:21.030","lastModified":"2026-09-04T13:19:26.440","vulnStatus":"Modified","cveTags":[],"descriptions":[{"lang":"en","value":"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 `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."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"handlebars-lang","product":"handlebars.js","versions":[{"version":">= 4.0.0, < 4.7.9","status":"affected"}]}]},{"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","affectedData":[{"vendor":"Red Hat","product":"Cluster Observability Operator 1.5.0","defaultStatus":"affected","collectionURL":"https://catalog.redhat.com/software/containers/","packageName":"cluster-observability-operator/logging-console-plugin-pf4-rhel9","cpes":["cpe:/a:redhat:cluster_observability_operator:1.5::el9"],"versions":[{"version":"1782839279","lessThan":"*","versionType":"rpm","status":"unaffected"}]},{"vendor":"Red Hat","product":"Cluster Observability Operator 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