CVE-2026-43512: Apache Tomcat authentication bypass in digest authentication

CVE-2026-43512 · Severity: critical · CVSS 9.8 · Published 2026-05-12

Apache Tomcat is a widely used web server and application container for Java applications. A security flaw in its Digest authentication mechanism allows unauthorized individuals to log in as any non-existent user by providing a specific password. This could allow attackers to bypass security controls and gain unauthorized access to protected web resources and data.

Technologies: Apache Tomcat, org.apache.tomcat:tomcat (Maven), org.apache.tomcat:tomcat-catalina (Maven), org.apache.tomcat.embed:tomcat-embed-core (Maven). Vendors: Apache, Maven.

Quick answers

Is CVE-2026-43512 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-43512 being exploited in the wild.
How severe is CVE-2026-43512?
Critical severity, with a CVSS score of 9.8, published 12 May 2026.
Which products and versions are affected?
Apache Tomcat 11.0.0-M1 to 11.0.21, 10.1.0-M1 to 10.1.54, 9.0.0.M1 to 9.0.117, 8.5.0 to 8.5.100, 7.0.0 to 7.0.109; org.apache.tomcat:tomcat (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118; org.apache.tomcat:tomcat-catalina (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118; org.apache.tomcat.embed:tomcat-embed-core (Maven) ECOSYSTEM:introduced=0,fixed=9.0.118.
Is there a fix for CVE-2026-43512?
Yes. org.apache.tomcat:tomcat (Maven): upgrade to 9.0.118 or later; org.apache.tomcat:tomcat-catalina (Maven): upgrade to 9.0.118 or later; org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 9.0.118 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-43512 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-43512?
Check whether you run Apache Tomcat, org.apache.tomcat:tomcat (Maven), org.apache.tomcat:tomcat-catalina (Maven) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • org.apache.tomcat:tomcat (Maven): upgrade to 9.0.118 or later
    # set org.apache.tomcat:tomcat to 9.0.118 in your pom.xml or build.gradle
  • org.apache.tomcat:tomcat-catalina (Maven): upgrade to 9.0.118 or later
    # set org.apache.tomcat:tomcat-catalina to 9.0.118 in your pom.xml or build.gradle
  • org.apache.tomcat.embed:tomcat-embed-core (Maven): upgrade to 9.0.118 or later
    # set org.apache.tomcat.embed:tomcat-embed-core to 9.0.118 in your pom.xml or build.gradle

Technical details

An authentication bypass vulnerability exists in Apache Tomcat's Digest authenticator. When Digest authentication is enabled, the system fails to correctly handle users not present in the configured Realm. If an attacker attempts to authenticate as a non-existent user and provides the string "null" as the password, the authenticator incorrectly validates the request. This allows a remote, unauthenticated attacker to bypass security constraints and gain access to protected resources. The issue is rooted in improper handling of null return values from the user realm during the digest calculation process. Patches are available in versions 11.0.22, 10.1.55, and 9.0.118.

Affected products

  • Apache Tomcat 11.0.0-M1 to 11.0.21, 10.1.0-M1 to 10.1.54, 9.0.0.M1 to 9.0.117, 8.5.0 to 8.5.100, 7.0.0 to 7.0.109

Identifiers

  • CVE-2026-43512
  • GHSA-h6fc-48rj-7qqh

Timeline

  • 2026-05-12: disclosed
  • 2026-05-12: advisory
  • 2026-05-18: patched: GitHub advisory reviewed and updated with patch information

References

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