CVE-2021-32637Network attack vector

Unauthenticated access via malformed target URL

Published May 28, 2021 · Updated Aug 3, 2024

Authentication bypass in Authelia 4.0.0-alpha1 through 4.29.2 allows remote attackers to reach nginx-protected resources. The VerifyGet handler treated a target-URL parsing failure as an HTTP 200 response instead of rejecting the request. Exploitation requires nginx ngx_http_auth_request_module to forward a malformed request URI; successful requests bypass access controls but do not directly interrupt service.

CVSS severity8.7
High
EPSS probability1.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Authelia 4.0.0-alpha1 through 4.29.2 allows remote attackers to reach nginx-protected resources. The VerifyGet handler treated a target-URL parsing failure as an HTTP 200 response instead of rejecting the request. Exploitation requires nginx ngx_http_auth_request_module to forward a malformed request URI; successful requests bypass access controls but do not directly interrupt service.

The record

CVE
CVE-2021-32637
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
Authelia
Product
Authelia
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.0.0-alpha1, < 4.29.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Authelia · Autheliaversion=>= 4.0.0-alpha1, < 4.29.3

Published CVSS scores

8.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
7.5NIST NVDAV: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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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