What’s Vulnerable › Vulnerabilities

CVE-2021-21335: Basic Authentication can be bypassed using a malformed username

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-08 · updated 2026-06-17
• Weakness: CWE-287

Description

In the SPNEGO HTTP Authentication Module for nginx (spnego-http-auth-nginx-module) before version 1.1.1 basic Authentication can be bypassed using a malformed username. This affects users of spnego-http-auth-nginx-module that have enabled basic authentication. This is fixed in version 1.1.1 of spnego-http-auth-nginx-module. As a workaround, one may disable basic authentication.

Affected products

• stnoonan spnego-http-auth-nginx-module: before 1.1.1 — fixed in 1.1.1

How to fix

Upgrade to a fixed version: stnoonan spnego-http-auth-nginx-module 1.1.1. Check the vendor advisory for mitigations.

References

• https://github.com/stnoonan/spnego-http-auth-nginx-module/commit/a06f9efca373e25328b1c53639a48decd0854570
• https://github.com/stnoonan/spnego-http-auth-nginx-module/releases/tag/v1.1.1
• https://github.com/stnoonan/spnego-http-auth-nginx-module/security/advisories/GHSA-ww8q-72rx-hc54
• https://github.com/stnoonan/spnego-http-auth-nginx-module/commit/a06f9efca373e25328b1c53639a48decd0854570
• https://github.com/stnoonan/spnego-http-auth-nginx-module/releases/tag/v1.1.1
• https://github.com/stnoonan/spnego-http-auth-nginx-module/security/advisories/GHSA-ww8q-72rx-hc54

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