CVE-2021-21335: In the SPNEGO HTTP Authentication Module for nginx (spnego-http-auth-nginx-module) before version 1.1.1 basic

Q: How do I fix CVE-2021-21335?

spnego http authentication module: upgrade to 1.1.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-21335 being exploited?

CVE-2021-21335 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-21335 affect?

CVE-2021-21335 affects spnego http authentication module. Severity is medium (CVSS 5.3). 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 b

Q: How urgent is CVE-2021-21335?

Priority 48/100. Remotely exploitable, no login, no user action; On your watchlist

This month

MEDIUM 5.3REMOTEWATCHLISTUPGRADE

CVE-2021-21335 is a medium-severity flaw (CVSS 5.3) affecting spnego http authentication module. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-287
Published	2021-03-08
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: spnego http authentication module project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-03-08 21:15 UTCPublished CVE record published
2026-06-17 03:35 UTCUpdated Record last modified

spnego http authentication module project spnego http authentication module UPGRADE

Affected: < 1.1.1

Fixed in: 1.1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy spnego-http-authentication-module || rpm -q spnego-http-authentication-module || spnego-http-authentication-module --version

2. UPGRADE to 1.1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade spnego-http-authentication-module

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade spnego-http-authentication-module

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-21335?

spnego http authentication module: upgrade to 1.1.1. Exact commands for each OS are on this page.

Is CVE-2021-21335 being exploited?

CVE-2021-21335 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-21335 affect?

CVE-2021-21335 affects spnego http authentication module. Severity is medium (CVSS 5.3). 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 b

How urgent is CVE-2021-21335?

Priority 48/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

nginx vulnerabilities

References

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