CVE-2026-56020 Webmin HTTP header authentication bypass
Remote attackers can bypass authentication and impersonate any user by forging HTTP headers when SSL client certificate authentication is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-56020?
CVE-2026-56020 is a critical authentication bypass vulnerability in Webmin, published on 18 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Webmin HTTP server (miniserv.pl) allows unauthenticated attackers to impersonate any user with a configured SSL client certificate by sending a forged HTTP header. A remote attacker can spoof certificate DNs and authenticate as any user. Fixed in 2.202.
Weakness: CWE-290
Which versions are affected by CVE-2026-56020?
How do I fix CVE-2026-56020?
No fix has been published for CVE-2026-56020 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-56020 being exploited?
There is no known exploitation of CVE-2026-56020 in the wild and no public exploit code.
Sources
Also known as GHSA-23xj-gfh3-wf2h.