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CRITICAL severity

CVE-2021-38384 — serverless-offline

CRITICAL

CVE-2021-38384 is a critical-severity (CVSS 9.8) CWE-755 vulnerability in serverless-offline. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Incorrect Authorization in serverless-offline

Also known asGHSA-h97f-5258-5593
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
1 known
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs73th percentile — riskier than 73% of all scored CVEsHighest risk
0.00%0.65%1.31%1.96%0.3%1.5%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-38384 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.

177other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
serverless-offlinenpm
628Kdownloads / week

Description

Serverless Offline 8.0.0 returns a 403 HTTP status code for a route that has a trailing / character, which might cause a developer to implement incorrect access control, because the actual behavior within the Amazon AWS environment is a 200 HTTP status code (i.e., possibly greater than expected permissions).

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
📦npmserverless-offlineall versionsNo fix

Affected Products

1 product · 1 configurations
Application
serverless offlineserverless_offline_project
1 version
8.0.0
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.

Serverless Offline 8.0.0 returns a 403 HTTP status code for a route that…

github.comNVDAug 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Remediation status

    No patched version of serverless-offline has shipped for CVE-2021-38384 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

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

Serverless Offline 8.0.0 returns a 403 HTTP status code for a route that has a trailing / character, which might cause a developer to implement incorrect access control, because the actual behavior within the Amazon AWS environment is a 200 HTTP status code (i.e., possibly greater than expected permissions).
O3 Security · Impact-Aware SCA

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CVE-2021-38384: serverless-offline: Incorrect Authorization