CVE-2021-38384Public exploitNetwork attack vector

Unauthorized API access via mismatched trailing-slash routing

Published Aug 10, 2021 · Updated Aug 4, 2024

Incorrect authorization emulation in Serverless Offline 8.0.0 allows remote attackers to access a trailing-slash API route in AWS. The custom-authorizer route evaluation returns 403 for a trailing-slash request that the equivalent API Gateway policy accepts with 200. This discrepancy affects developers who rely on the local denial when defining wildcard resource policies, leaving the deployed route accessible beyond the tested expectation.

CVSS severity9.8
Critical
EPSS probability1.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization emulation in Serverless Offline 8.0.0 allows remote attackers to access a trailing-slash API route in AWS. The custom-authorizer route evaluation returns 403 for a trailing-slash request that the equivalent API Gateway policy accepts with 200. This discrepancy affects developers who rely on the local denial when defining wildcard resource policies, leaving the deployed route accessible beyond the tested expectation.

The record

CVE
CVE-2021-38384
Published
Aug 10, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755, CWE-863, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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