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Apache Tomcat - Digest authenticator will authenticate any unknown user

Critical severity GitHub Reviewed Published May 12, 2026 to the GitHub Advisory Database • Updated May 18, 2026

Package

maven org.apache.tomcat.embed:tomcat-embed-core (Maven)

Affected versions

< 9.0.118
>= 10.1.0-M1, < 10.1.55
>= 11.0.0-M1, < 11.0.22

Patched versions

9.0.118
10.1.55
11.0.22
maven org.apache.tomcat:tomcat (Maven)
< 9.0.118
>= 10.1.0-M1, < 10.1.55
>= 11.0.0-M1, < 11.0.22
9.0.118
10.1.55
11.0.22
maven org.apache.tomcat:tomcat-catalina (Maven)
< 9.0.118
>= 10.1.0-M1, < 10.1.55
>= 11.0.0-M1, < 11.0.22
9.0.118
10.1.55
11.0.22

Description

Versions Affected:
Apache Tomcat 11.0.0-M1 to 11.0.21
Apache Tomcat 10.1.0-M1 to 10.1.54
Apache Tomcat 9.0.0.M1 to 9.0.117
Older, unsupported versions may also be affected

Description:
When DIGEST authentication was configured, any user not known to the
configured Realm would be authenticated if they presented the password
"null".

Mitigation:
Users of the affected versions should apply one of the following
mitigations:

  • Upgrade to Apache Tomcat 11.0.22 or later
  • Upgrade to Apache Tomcat 10.1.55 or later
  • Upgrade to Apache Tomcat 9.0.118 or later

References

Published by the National Vulnerability Database May 12, 2026
Published to the GitHub Advisory Database May 12, 2026
Reviewed May 18, 2026
Last updated May 18, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(34th percentile)

Weaknesses

Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Learn more on MITRE.

CVE ID

CVE-2026-43512

GHSA ID

GHSA-h6fc-48rj-7qqh

Source code

No known source code
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