Vulnerability in handlebars (CVE-2026-106444)
Summary
Vulnerability in handlebars (CVE-2026-106444). Risk of unauthorized operations or information disclosure. Exploitable via true. Mitigation: upgrade to 4.7.10 or later.
Original description
The description as published by the source.
Summary
Handlebars.precompile() generates JavaScript source that is commonly embedded in browser elements. Before the fix, static template text containing was emitted unchanged. HTML parsers recognize `` even inside a JavaScript string literal, closing the surrounding script element and allowing following attacker-controlled markup to be parsed and executed.
This affects applications that precompile attacker-controlled templates and embed the generated source directly in an HTML `` element. It does not affect ordinary server-side rendering or precompiled templates delivered as external JavaScript files.
Details
Static text is serialized by quotedString() in lib/handlebars/compiler/code-gen.js. The generated JavaScript is valid, but JavaScript quoting alone does not make it safe to embed in HTML. In HTML script data, the sequence `` terminates the element regardless of JavaScript string context.
On affected releases, this template:
safealert("XSS")
could produce generated source containing:
return 'safealert("XSS")';
When included inline in an HTML document, the first closes the script containing the precompiled template. The next element is then parsed as HTML and executes.
Proof of Concept
const Handlebars = require('handlebars');
const template = 'safealert("XSS")';
const output = Handlebars.precompile(template);
console.log(output.includes(''));
Affected versions print true. Embedding output…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-106444 has been found in handlebars.
Attackers can target a specific entry point like true over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.7/10.
What to do: upgrade handlebars to 4.7.10 or later.
If unsure, ask your IT team or search "handlebars CVE-2026-106444" on the vendor's site.
CVE-2026-106444 (handlebars) — CWE-116 / CVSS v3 4.7
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: true / output
Patched: 4.7.10 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-116) exists in handlebars. Attackers reach the vulnerable code path via true without authentication.
Check the vendor advisory for the affected versions of handlebars. Attack surface: true / output.
Severity: Medium (CVSS 4.7/10). Risk of unauthorized operations or information disclosure.
Update to 4.7.10.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'handlebars' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'handlebars' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
handlebarsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade handlebars to 4.7.10ステージング環境で 4.7.10 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-106444 ruby-handlebars-assets
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com