Vulnerability-Lookup

FKIE_CVE-2026-33939

Vulnerability from fkie_nvd - Published: 2026-03-27 22:16 - Updated: 2026-09-04 13:19

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

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.

References

URL	Tags
security-advisories@github.com	https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2	Patch
security-advisories@github.com	https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9	Release Notes
security-advisories@github.com	https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff	Exploit, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:10175
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/errata/RHSA-2026:34342
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://access.redhat.com/security/cve/CVE-2026-33939
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://bugzilla.redhat.com/show_bug.cgi?id=2452508
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff	Exploit, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46c	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33939.json

Impacted products

	Vendor	Product	Version
	handlebarsjs	handlebars	*

JSON

To clipboard

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          "cpes": [
            "cpe:/a:redhat:openshift_ai"
          ],
          "defaultStatus": "unaffected",
          "packageName": "rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9",
          "product": "Red Hat OpenShift AI (RHOAI)",
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        },
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          "cpes": [
            "cpe:/a:redhat:jboss_enterprise_bpms_platform:7"
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    }
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    }
  ],
  "id": "CVE-2026-33939",
  "lastModified": "2026-09-04T13:19:26.173",
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          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
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          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
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          "userInteraction": "NONE",
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}

CVE-2026-33939 (GCVE-0-2026-33939)

Vulnerability from cvelistv5 – Published: 2026-03-27 21:08 – Updated: 2026-09-04 12:04

Title

Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation

Summary

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-30 18:52 UTC

CWE

CWE-754 - Improper Check for Unusual or Exceptional Conditions
CWE-248 - Uncaught Exception

Assigner

GitHub_M mitre root

References

8 references

URL	Tags
https://github.com/handlebars-lang/handlebars.js/…	x_refsource_CONFIRM
https://github.com/handlebars-lang/handlebars.js/…	x_refsource_MISC
https://github.com/handlebars-lang/handlebars.js/…	x_refsource_MISC
https://access.redhat.com/security/cve/CVE-2026-33939	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2452508	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:34342	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:10175	vendor-advisoryx_refsource_REDHAT

Impacted products

14 products

Vendor	Product	Version
handlebars-lang	handlebars.js	Affected: >= 4.0.0, < 4.7.9
Red Hat	Cluster Observability Operator 1.5.0	Unaffected: 1782839279 , < * (rpm) cpe:/a:redhat:cluster_observability_operator:1.5::el9
Red Hat	Cluster Observability Operator 1.5.0	Unaffected: 1782840539 , < * (rpm) cpe:/a:redhat:cluster_observability_operator:1.5::el9
Red Hat	Cluster Observability Operator 1.5.0	Unaffected: 1782839996 , < * (rpm) cpe:/a:redhat:cluster_observability_operator:1.5::el9
Red Hat	Red Hat OpenShift Dev Spaces 3.27	Unaffected: 1776744110 , < * (rpm) cpe:/a:redhat:openshift_devspaces:3.27::el9
Red Hat	Cryostat 4	cpe:/a:redhat:cryostat:4
Red Hat	Logging Subsystem for Red Hat OpenShift	cpe:/a:redhat:logging:5
Red Hat	Red Hat Data Grid 8	cpe:/a:redhat:jboss_data_grid:8
Red Hat	Red Hat Enterprise Linux 10	cpe:/o:redhat:enterprise_linux:10
Red Hat	Red Hat Enterprise Linux 7	cpe:/o:redhat:enterprise_linux:7
Red Hat	Red Hat Enterprise Linux 8	cpe:/o:redhat:enterprise_linux:8
Red Hat	Red Hat Enterprise Linux 9	cpe:/o:redhat:enterprise_linux:9
Red Hat	Red Hat OpenShift AI (RHOAI)	cpe:/a:redhat:openshift_ai
Red Hat	Red Hat Process Automation 7	cpe:/a:redhat:jboss_enterprise_bpms_platform:7

Show details on NVD website

JSON

To clipboard

{
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        "metrics": [
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            "other": {
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                "id": "CVE-2026-33939",
                "options": [
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                  },
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                "role": "CISA Coordinator",
                "timestamp": "2026-03-30T18:52:18.558792Z",
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        "discovery": "UNKNOWN"
      },
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    }
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    "dateReserved": "2026-03-24T19:50:52.103Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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FKIE_CVE-2026-33939

CVE-2026-33939 (GCVE-0-2026-33939)

Tags

Sightings

Nomenclature

Related by attack behaviour