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MEDIUM severity

Insecure template handling in express-hbsGHSA-rwxp-hwwf-653v

MEDIUMFix: TryGhost/express-hbs@ff6fad6

GHSA-rwxp-hwwf-653v is a medium-severity (CVSS 5.4) Information Exposure vulnerability in express-hbs. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Also known asBIT-handlebars-2021-32817CVE-2021-32817
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Sep 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk

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

How urgent is this, really

GHSA-rwxp-hwwf-653v 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.

142other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
express-hbsnpm
25Kdownloads / week

Description

express-hbs is an Express handlebars template engine. express-hbs mixes pure template data with engine configuration options through the Express render API. More specifically, the layout parameter may trigger file disclosure vulnerabilities in downstream applications. This potential vulnerability is somewhat restricted in that only files with existing extentions (i.e. file.extension) can be included, files that lack an extension will have .hbs appended to them. For complete details refer to the referenced GHSL-2021-019 report. Notes in documentation have been added to help users of express-hbs avoid this potential information exposure vulnerability.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmexpress-hbsall versionsNo fix

Affected Products

1 product · 1 configurations
Application
express handlebarsexpress_handlebars_project
≤ 5.3.2
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

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

  2. Remediation status

    No patched version of express-hbs has shipped for GHSA-rwxp-hwwf-653v yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

express-hbs is an Express handlebars template engine. express-hbs mixes pure template data with engine configuration options through the Express render API. More specifically, the layout parameter may trigger file disclosure vulnerabilities in downstream applications. This potential vulnerability is somewhat restricted in that only files with existing extentions (i.e. file.extension) can be included, files that lack an extension will have .hbs appended to them. For complete details refer to the referenced GHSL-2021-019 report. Notes in documentation have been added to help users of express-hbs
O3 Security · Impact-Aware SCA

Is GHSA-rwxp-hwwf-653v in your dependencies?

Find it across npm, including transitive dependencies.

Insecure template handling in express-hbs (Medium 5.4)