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HIGH severity

CVE-2019-20922 — handlebars

HIGHFix: handlebars-lang/handlebars.js@8d5530e

CVE-2019-20922 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in handlebars. A fix is available for handlebars — see the affected versions and patch details below.

Regular Expression Denial of Service in Handlebars

Also known asGHSA-62gr-4qp9-h98fSNYK-JS-HANDLEBARS-480388
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
3.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk
0.00%1.61%3.23%4.84%0.3%3.7%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2019-20922 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

17Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
handlebarsnpm
41.5Mdownloads / week

Description

Handlebars before 4.4.5 allows Regular Expression Denial of Service (ReDoS) because of eager matching. The parser may be forced into an endless loop while processing crafted templates. This may allow attackers to exhaust system resources.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmhandlebars≥ 4.0.0&&< 4.4.54.4.5npm install handlebars@4.4.5

Affected Products

1 product · 1 configurations
Application
handlebarshandlebarsjs
≥ 4.0.0 && < 4.4.5
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for handlebars, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update handlebars to 4.4.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-20922 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

Handlebars before 4.4.5 allows Regular Expression Denial of Service (ReDoS) because of eager matching. The parser may be forced into an endless loop while processing crafted templates. This may allow attackers to exhaust system resources.
O3 Security · Impact-Aware SCA

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CVE-2019-20922: handlebars DoS — Fixed in 4.4.5