CVE-2026-86247
HIGHDescription
Race condition within a thread vulnerability in Apache Tomcat Native allowed client certificate verification requirements to be down-graded for some configurations. This issue affects Apache Tomcat Native: from 2.0.0 through 2.0.15, from 1.3.0 through 1.3.8. Unsupported versions may also be affected. Users are recommended to upgrade to version 2.0.16 or 1.3.9, which fixes the issue.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 11% of all known CVEs.
References
Related Vulnerabilities
Other CWE-366 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-26569 | Critical | 9.8 | 2.3% | - | Fix |
| CVE-2026-23666 | Critical | 7.5 | 1.3% | - | - |
| CVE-2024-6778 | High | 7.5 | 0.8% | - | Fix |
| CVE-2023-6546 | High | 7.0 | 0.7% | - | Fix |
| CVE-2020-1629 | Medium | 5.9 | 0.7% | - | - |
| CVE-2025-31115 | High | - | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-86247?
Upgrade tomcat-native on debian unstable to 2.0.16-1 or later.
Is CVE-2026-86247 being actively exploited?
Not that we know of. CVE-2026-86247 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.22% is the estimated probability that it will be exploited in the next 30 days. That is higher than 11% of all scored CVEs.
How severe is CVE-2026-86247?
CVE-2026-86247 has a CVSS v3 base score of 7.4, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-86247 affect?
Published advisories record a fix for tomcat-native (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-06.