CVE-2021-32637

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 1.9%, top 23% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
10.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 10.0Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
10.0
EG Score
10.0(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
77.1%
KEV
Not listed

Published

May 28, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Jul 18, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Authentication bypassed with malformed request URI on nginx · Advisory · authelia/authelia · GitHub

https://github.com/authelia/authelia/security/advisories/GHSA-68wm-pfjf-wqp6
github_commit

commit c62dbd43d6e6 (authelia/authelia)

Fix landed in authelia/authelia commit c62dbd43d6e6 — awaiting tagged release

https://github.com/authelia/authelia/commit/c62dbd43d6e69ae81530e7c4f8763857f8ff1dda

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/authelia/authelia/v4—4.29.3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 16× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-32637?
CVE-2021-32637 is a critical vulnerability published on May 28, 2021. Authelia is a a single sign-on multi-factor portal for web apps. This affects uses who are using nginx ngxhttpauthrequestmodule with Authelia, it allows a malicious individual who crafts a malformed HTTP request to bypass the authentication mechanism. It additionally could theoretically affect…
When was CVE-2021-32637 disclosed?
CVE-2021-32637 was first published in the National Vulnerability Database on May 28, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-32637 actively exploited?
CVE-2021-32637 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-32637?
CVE-2021-32637 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2021-32637?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-32637, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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