CVE-2026-43512 is a critical-severity (CVSS 9.8) CWE-592 vulnerability in org.apache.tomcat.embed:tomcat-embed-core. A fix is available for org.apache.tomcat.embed:tomcat-embed-core — see the affected versions and patch details below.
Apache Tomcat: Digest authenticator will authenticate any unknown user
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-43512.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat.embed:tomcat-embed-core☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat☕org.apache.tomcat:tomcat-catalina☕org.apache.tomcat:tomcat-catalina+1 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | all versions | 9.0.118org.apache.tomcat.embed:tomcat-embed-core:9.0.118 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 10.1.0-M1&&< 10.1.55 | 10.1.55org.apache.tomcat.embed:tomcat-embed-core:10.1.55 |
| ☕Maven | org.apache.tomcat.embed:tomcat-embed-core | ≥ 11.0.0-M1&&< 11.0.22 | 11.0.22org.apache.tomcat.embed:tomcat-embed-core:11.0.22 |
| ☕Maven | org.apache.tomcat:tomcat | all versions | 9.0.118org.apache.tomcat:tomcat:9.0.118 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 10.1.0-M1&&< 10.1.55 | 10.1.55org.apache.tomcat:tomcat:10.1.55 |
| ☕Maven | org.apache.tomcat:tomcat | ≥ 11.0.0-M1&&< 11.0.22 | 11.0.22org.apache.tomcat:tomcat:11.0.22 |
Affected Products
tomcatapacheDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat.embed:tomcat-embed-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.tomcat.embed:tomcat-embed-core to 9.0.118 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-43512 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This Moderate flaw in Apache Tomcat allows an authentication bypass when DIGEST authentication is configured. An attacker can authenticate as any unknown user by providing the password 'null', potentially gaining unauthorized access to applications protected by DIGEST authentication. Red Hat products are only affected…
To mitigate this issue, disable DIGEST authentication within Apache Tomcat if it is not essential for your environment. This involves modifying the server's authentication configuration to utilize alternative methods or remove the DIGEST realm. A service restart is required for these changes to take effect and may impact functionality relying on DIGEST authentication.Source: Red Hat security advisory for CVE-2026-43512 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | tomcat9-1:9.0.120-1.el10_2 | RHSA-2026:68651 |
| Red Hat Enterprise Linux 10 | tomcat-1:10.1.49-4.el10_2 | RHSA-2026:69259 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | tomcat9-1:9.0.120-1.el10_0 | RHSA-2026:67163 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | tomcat-1:10.1.49-1.el10_0 | RHSA-2026:67164 |
| Red Hat Enterprise Linux 8 | tomcat-1:9.0.120-1.el8_10 | RHSA-2026:68677 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | tomcat-1:9.0.120-1.el8_8 | RHSA-2026:68680 |
| Red Hat Enterprise Linux 9 | tomcat-1:9.0.120-2.el9_8 | RHSA-2026:68660 |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | tomcat-1:9.0.120-1.el9_2 | RHSA-2026:68678 |
Frequently Asked Questions
Is CVE-2026-43512 in your dependencies?
Find it across Maven, including transitive dependencies.