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No exploitation reportedFix available

CVE-2021-32637

No exploitation reported by the sources we read.

  • Published2021-05-28
  • Fixed in4.29.3 · 4.25.1
  • WeaknessCWE-287

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Authelia is a a single sign-on multi-factor portal for web apps. This affects uses who are using nginx ngx_http_auth_request_module with Authelia, it allows a malicious individual who crafts a malformed HTTP request to bypass the authentication mechanism. It additionally could theoretically affect other proxy servers, but all of the ones we officially support except nginx do not allow malformed URI paths. The problem is rectified entirely in v4.29.3. As this patch is relatively straightforward we can back port this to any version upon request. Alternatively we are supplying a git patch to 4.25.1 which should be relatively straightforward to apply to any version, the git patches for specific versions can be found in the references. The most relevant workaround is upgrading. You can also add a block which fails requests that contains a malformed URI in the internal location block.

Timeline

dates in UTC
  1. 2021-05-2817:15CVE publishedNVD

Versions per branch

NVD · OSV
Authelia
BranchAffectedFixed in
4.x≥ 4.26.0, < 4.29.34.29.3
4.x≥ 4.0.0-alpha1, < 4.29.34.29.3
4.x≥ 4.0.0, < 4.25.14.25.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Authelia to 4.29.3 · 4.25.1

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.110known since 2026-10-23
  • NVDCVSS 3.110read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • CNAweakness (CWE)CWE-287known since 2026-10-23
  • FIRST EPSSEPSS score1.9 %2026-11-08
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryCRITICAL2021-05-28

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Published
2021-05-28
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-68wm-pfjf-wqp6

Frequently asked questions

What is CVE-2021-32637?

Authelia is a a single sign-on multi-factor portal for web apps. This affects uses who are using nginx ngx_http_auth_request_module with Authelia, it allows a malicious individual who crafts a malformed HTTP request to bypass the authentication mechanism. It additionally could theoretically affect other proxy servers, but all of the ones we officially support except nginx do not allow malformed URI paths. The problem is rectified entirely in v4.29.3. As this patch is relatively straightforward we can back port this to any version upon request. Alternatively we are supplying a git patch to 4.25.1 which should be relatively straightforward to apply to any version, the git patches for specific versions can be found in the references. The most relevant workaround is upgrading. You can also add a block which fails requests that contains a malformed URI in the internal location block.

Is CVE-2021-32637 actively exploited?

Active exploitation of CVE-2021-32637 has not been confirmed. Its EPSS score was 1.9% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-32637?

CVE-2021-32637 has a CVSS v3 base score of 10 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

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