---
title: "CVE-2026-106445: Handlebars - Server-Side Template Injection"
description: "Handlebars 4.0.0 to 4.7.10 contains a server-side template injection caused by lookupProperty returning Function.prototype.constructor before applying prototype-access deny list, letting attackers execute arbitrary JavaScript with server privileges, exploit requires allowProtoMethodsByDefault enabled and accessible function in template context."
url: https://panop.io/threat-heartbeat/CVE-2026-106445/
---

# CVE-2026-106445 Handlebars - Server-Side Template Injection

Handlebars 4.0.0 to 4.7.10 contains a server-side template injection caused by lookupProperty returning Function.prototype.constructor before applying prototype-access deny list, letting attackers execute arbitrary JavaScript with server privileges, exploit requires allowProtoMethodsByDefault enabled and accessible function in template context.

CVSS base score 9.2 /10

Critical

CISA KEV

Not listed

Public exploit

Proof of concept available

Authentication

Not required

EPSS

0.41% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-106445)

## Details

Type

Server-Side Template Injection

Impact

Remote Code Execution

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Published

6 October 2026

Updated

15 October 2026

Weakness

[CWE-184](https://cwe.mitre.org/data/definitions/184.html)

## Vendor fix

Update to version 4.7.10 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-106445](https://nvd.nist.gov/vuln/detail/CVE-2026-106445)
- [https://github.com/handlebars-lang/handlebars.js/commit/ceec388abe1d1aac8f6369860d5f390fa71ef4fa](https://github.com/handlebars-lang/handlebars.js/commit/ceec388abe1d1aac8f6369860d5f390fa71ef4fa)
- [https://github.com/handlebars-lang/handlebars.js/pull/2185](https://github.com/handlebars-lang/handlebars.js/pull/2185)
- [https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10](https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10)
- [https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f](https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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