Vulnerability-Lookup

CVE-2026-87123 (GCVE-0-2026-87123)

Vulnerability from cvelistv5 – Published: 2026-09-11 09:50 – Updated: 2026-09-11 10:29

Title

hbs vulnerable to Denial of Service via unhandled exception in async helper output escaping

Summary

hbs is an Express view engine wrapper for Handlebars. Version 4.3.0 can crash the Node.js process during output escaping when an async helper, registered with registerAsyncHelper, resolves to an object whose toHTML property is truthy but not callable. Handlebars escapeExpression calls the toHTML method on any value that has a truthy toHTML, so such a value throws a TypeError, and because the async substitution runs on a later tick outside the render function's try/catch, the throw is an uncaught exception that terminates the process without sending a response. Only version 4.3.0 is affected, since the throwing escape was introduced by the fix for CVE-2026-16231 and earlier versions do not escape async helper values. It can be triggered remotely when an async helper resolves to an externally influenced object such as parsed JSON. The issue is fixed in hbs 4.3.1, and users should upgrade to hbs 4.3.1 or later.

Severity

5.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-11 10:28 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

openjs redhat root

References

2 references

URL	Tags
https://github.com/pillarjs/hbs/security/advisori…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version	CPE status
hbs	hbs	Affected: 4.3.0 , < 4.3.1 (semver) Unaffected: 4.3.1 (semver)	guessed

Credits

mfdebian UlisesGascon bjohansebas official-burak

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-87123

Vulnerability from fkie_nvd - Published: 2026-09-11 10:16 - Updated: 2026-09-11 11:16

Severity

5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	ce714d77-add3-4f53-aff5-83d477b104bb	https://cna.openjsf.org/security-advisories.html
	ce714d77-add3-4f53-aff5-83d477b104bb	https://github.com/pillarjs/hbs/security/advisories/GHSA-3c55-w9jx-p5jr

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "defaultStatus": "unaffected",
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          "product": "hbs",
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    }
  ],
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  "lastModified": "2026-09-11T11:16:57.387",
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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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

CVE-2026-87123 (GCVE-0-2026-87123)

FKIE_CVE-2026-87123

Tags

Sightings

Nomenclature