CVE-2026-43512Network attack vector

Authentication bypass via unknown-user null digest

Published May 12, 2026 · Updated May 12, 2026

DIGEST authentication bypass in affected Apache Tomcat releases allows remote attackers to access protected resources as unknown users. RealmBase.getDigest converts a missing realm password into the literal null value within the A1 digest instead of rejecting the unknown username. Reachability requires DIGEST authentication, and access remains bounded by the resources and role constraints applied to the authenticated request.

CVSS severity9.8
Critical
EPSS probability1.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DIGEST authentication bypass in affected Apache Tomcat releases allows remote attackers to access protected resources as unknown users. RealmBase.getDigest converts a missing realm password into the literal null value within the A1 digest instead of rejecting the unknown username. Reachability requires DIGEST authentication, and access remains bounded by the resources and role constraints applied to the authenticated request.

The record

CVE
CVE-2026-43512
Published
May 12, 2026
Updated
May 12, 2026
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-592, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.1.0-M1 <=10.1.54
  2. Affected versionversion=11.0.0-M1 <=11.0.21
  3. Affected versionversion=7.0.0 <=7.0.109
  4. Affected versionversion=8.5.0 <=8.5.100
  5. Affected versionversion=9.0.0.M1 <=9.0.117

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.1.0-M1 <=10.1.54; version=11.0.0-M1 <=11.0.21; version=7.0.0 <=7.0.109; version=8.5.0 <=8.5.100; version=9.0.0.M1 <=9.0.117

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-592DEPRECATED: Authentication Bypass Issues
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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