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Fencer Vulns
critical 9.2

CVE-2026-106445 json

Handlebars: JavaScript Injection via Own Property Check Bypass

published 2026-10-06 33 d ago modified 2026-10-12 28 d ago also EUVD-2026-93952 , GHSA-p8wg-vrv2-v86f

cvss
9.2
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm handlebars 4.7.10
  • handlebarsjs handlebars 4.7.10
  • handlebars.js_project handlebars.js 4.7.10
  • node-handlebars Debian 14 3:4.7.10-1

debian advisories DEBIAN-CVE-2026-106445

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-106445 updated cvss 8.1

handlebars: Handlebars: JavaScript Injection via Own Property Check Bypass

  • Red Hat Node HealthCheck Operator workload-availability/node-remediation-console-rhel8, workload-availability/node-healthcheck-rhel9-operator, workload-availability/node-healthcheck-operator-bundle, workload-availability/node-healthcheck-must-gather-rhel9 Red Hat AMQ Broker 7 amq-broker-maven-repository.zip Red Hat Enterprise Linux 8 cockpit, mozjs60, cockpit-ws, cockpit-pcp, cockpit-bridge, cockpit-system, +4 more Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-operator-rhel9, rhoai/odh-mod-arch-agent-ops-rhel9 Red Hat OpenShift Dev Spaces devspaces/dashboard-rhel9 Red Hat Quay 3 quay/quay-rhel8
    +1 more products
    Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal
    affected: workaround, no fix available “Do not set allowProtoMethodsByDefault to true when compiling or rendering untrusted templates or untrusted data.”
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-openshift-console-plugin-rhel9 4.2.0-19
    fixed: vendor fix “Do not set allowProtoMethodsByDefault to true when compiling or rendering untrusted templates or untrusted data.” RHSA-2026:95360
  • Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/console-mce-rhel9 1792886718
    fixed: vendor fix “Do not set allowProtoMethodsByDefault to true when compiling or rendering untrusted templates or untrusted data.” RHSA-2026:92303
  • Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/console-rhel9 1792883111
    fixed: vendor fix “Do not set allowProtoMethodsByDefault to true when compiling or rendering untrusted templates or untrusted data.” RHSA-2026:92307
  • Red Hat OpenShift AI 3.4 rhoai/odh-dashboard-rhel9 1793001801, rhoai/odh-mod-arch-maas-rhel9 1793001859, rhoai/odh-mod-arch-automl-rhel9 1793001841, rhoai/odh-mod-arch-gen-ai-rhel9 1793001896, rhoai/odh-mod-arch-mlflow-rhel9 1793001851, rhoai/odh-mod-arch-autorag-rhel9 1793001850, +2 more
    fixed: vendor fix “Do not set allowProtoMethodsByDefault to true when compiling or rendering untrusted templates or untrusted data.” RHSA-2026:92510
  • Red Hat Cryostat 4 on RHEL 9 cryostat/cryostat-rhel9 4.2.0-18, cryostat/cryostat-db-rhel9 4.2.0-29, cryostat/jfr-datasource-rhel9 4.2.0-19, cryostat/cryostat-reports-rhel9 4.2.0-19, cryostat/cryostat-storage-rhel9 4.2.0-28, cryostat/cryostat-rhel9-operator 4.2.0-29, +3 more Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/hive-rhel9 1793055767, multicluster-engine/work-rhel9 1792867410, multicluster-engine/discovery-rhel9 1792864323, multicluster-engine/placement-rhel9 1792887454, multicluster-engine/must-gather-rhel9 1792838494, multicluster-engine/registration-rhel9 1792885410, +20 more Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/thanos-rhel9 1792872550, rhacm2/acm-cli-rhel9 1792972427, rhacm2/prometheus-rhel9 1792853139, rhacm2/acm-grafana-rhel9 1792865487, rhacm2/acm-search-v2-rhel9 1792847370, rhacm2/node-exporter-rhel9 1792872412, +37 more Red Hat AMQ Broker 7 amq-broker-bin.zip
    not affected: vulnerable code not present
  • Red Hat build of Apache Camel - HawtIO 4 rhaf-hawtio-maven-repository.zip
    not affected: vulnerable code not in execute path
  • Red Hat build of Apache Camel for Spring Boot 4 rhaf-camel-maven-repository.zip, rhaf-camel-spring-boot-maven-repository.zip, rhaf-camel-for-springboot-maven-repository.zip
    not affected: component not present
show 6 more
  • Red Hat Data Grid 8 redhat-datagrid-maven-repository.zip
    not affected: vulnerable code cannot be controlled by adversary
  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9 Red Hat Enterprise Linux 7 firefox
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux 8 rls, rust, cargo, clippy, dotnet, grafana, +39 more Red Hat Enterprise Linux 9 rust, cargo, goose, clippy, firefox, grafana, +29 more Red Hat Enterprise Linux 10 rust, goose, firefox, grafana, wayland, dotnet8.0, +1 more
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rust
    not affected: vulnerable code not present
  • Red Hat Hardened Images rust, yarnpkg, dotnet8.0, grafana12.4, grafana13.1, grafana13.2, +1 more
    not affected: component not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 Red Hat OpenShift AI 3.4 rhoai/odh-cli-rhel9 1792722177, rhoai/rhai-cli-rhel9 1792722177, rhoai/odh-automl-rhel9 1792697253, rhoai/odh-mlflow-rhel9 1793002327, rhoai/odh-autorag-rhel9 1793265800, rhoai/odh-trainer-rhel9 1792817113, +92 more Red Hat OpenShift Dev Spaces devspaces/code-rhel9 Red Hat OpenShift Update Service openshift-update-service/openshift-update-service-rhel8 Red Hat Trusted Profile Analyzer rhtpa/rhtpa-trustification-service-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
31 d ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.2 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
CNA 4.0 9.2 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

Affected packages

ecosystem package affected fixed in
npm handlebars
>=3.0.0, <4.7.10
4.7.10

Affected products

  • handlebars-lang handlebars.js

Classification

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

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.