CVE-2026-56022: Webmin accepts basic authentication without session cookies when an attacker provides the 'User-Agent: webmin'

Q: How do I fix CVE-2026-56022?

webmin: upgrade to 2.640. Exact commands for each OS are on this page.

Q: Is CVE-2026-56022 being exploited?

CVE-2026-56022 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-2026-56022 affect?

CVE-2026-56022 affects webmin. Severity is medium (CVSS 5.3). Webmin accepts basic authentication without session cookies when an attacker provides the 'User-Agent: webmin' header, allowing bypass of additional MFA requirements. Fixed in 2.640.

Q: How urgent is CVE-2026-56022?

Priority 35/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-56022 is a medium-severity flaw (CVSS 5.3) affecting webmin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Webmin accepts basic authentication without session cookies when an attacker provides the 'User-Agent: webmin' header, allowing bypass of additional MFA requirements. Fixed in 2.640.

Why this priority

Remotely exploitable, no login, no user action

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	0.6% (top 54%)
CISA exploited list	No
Weakness	CWE-308
Published	2026-06-18
Last modified	2026-08-11

Publisher (CNA): Cybersecurity and Infrastructure Security Agency (CISA) U.S. Civilian Government · Vendor: webmin

Last updated 2026-08-11 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-18 17:16 UTCPublished CVE record published
2026-08-11 17:05 UTCUpdated Record last modified

webmin webmin UPGRADE

Affected: < 2.640

Fixed in: 2.640

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy webmin || rpm -q webmin || webmin --version

2. UPGRADE to 2.640 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade webmin

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade webmin

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-2026-56022?

webmin: upgrade to 2.640. Exact commands for each OS are on this page.

Is CVE-2026-56022 being exploited?

CVE-2026-56022 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-2026-56022 affect?

CVE-2026-56022 affects webmin. Severity is medium (CVSS 5.3). Webmin accepts basic authentication without session cookies when an attacker provides the 'User-Agent: webmin' header, allowing bypass of additional MFA requirements. Fixed in 2.640.

How urgent is CVE-2026-56022?

Priority 35/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-56021 MEDIUM 5.3 UPGRADE Webmin allows unauthenticated attackers to read the contents of any file ending in .conf within module directo

References

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