CVE-2026-86247
HIGH 7.4Race 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.
Severe if exploited (CVSS 7.4), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 11th percentile
Impact if exploited
7.4CVSS 3.1 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ⚠Complexity: Needs a race window or specific setup
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-86247/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-86247/poc.json
Weakness (CWE)
- CWE-366: Race condition within a thread
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Apache | Tomcat Native | ≥ 1.3.0 and < 1.3.9 |
| Apache | Tomcat Native | ≥ 2.0.0 and < 2.0.16 |
All CVSS metrics
- HIGH 7.4 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - HIGH 7.4 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N