CVE-2026-43515 is a critical-severity (CVSS 9.1) CWE-285 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: Security constraints not correctly applied
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-2026-43515.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-43515 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 multiple security constraints defined an HTTP method constraint for the same extension pattern, only the first method constraint was applied.
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 |
Detection & 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-2026-43515 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-43515 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-43515. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
| 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-2026-43515 in your dependencies?
O3 Security finds CVE-2026-43515 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.