VulnTideExploited vulnerabilities, by vendor. Data as of .
Not in CISA KEVPublished CVSS 9.2 criticalEPSS 0.6% probability of exploitation in 30 days
handlebars-lang

CVE-2026-106445: Handlebars: JavaScript Injection via Own Property Check Bypass

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?
0.6%

EPSS score, percentile 48.1 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?
9.2 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • >= 3.0.0, < 4.7.10

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

What to do

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Affected products and versions

As listed in the CVE record.

handlebars-lang handlebars.js
StatusVersions
Affected>= 3.0.0, < 4.7.10

Source: CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

About this vulnerability

Handlebars provides the power necessary to let users build semantic templates. From 3.0.0 until 4.7.10, Handlebars lookupProperty returns Function.prototype.constructor before applying the prototype-access deny list because constructor is an own property of Function.prototype. When an attacker can render a controlled template with allowProtoMethodsByDefault enabled and an accessible function in t…

Summary: CVE record, as of .

  • CISA has not added CVE-2026-106445 to its Known Exploited Vulnerabilities (KEV) catalog, as of 28 Oct 2026.
  • The CVE record was published on 6 Oct 2026.
  • The CVE record carries a CVSS v4.0 base score of 9.2 (Critical), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.6% (percentile 48.1), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
  • CISA's SSVC assessment in the CVE record: exploitation poc, automatable yes, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

Handlebars: JavaScript Injection via Own Property Check Bypass

Handlebars provides the power necessary to let users build semantic templates. From 3.0.0 until 4.7.10, Handlebars lookupProperty returns Function.prototype.constructor before applying the prototype-access deny list because constructor is an own property of Function.prototype. When an attacker can render a controlled template with allowProtoMethodsByDefault enabled and an accessible function in the template context, the template can traverse from that function through its prototype to Function.prototype and then obtain the Function constructor through the own-property bypass. This permits attacker-controlled JavaScript to execute with the server application's privileges. This issue is fixed in version 4.7.10.

Source: CVE List V5 (CVE Program), cve_2026-10-29_0000Z, as of . About the data.

Weakness

  • CWE-184: Incomplete List of Disallowed Inputs
  • CWE-1289: Improper Validation of Unsafe Equivalence in Input

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.

Timeline

DateEvent
CVE record published
CVE record last updated

References