CVE-2026-55276
CRITICAL 9.1Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisation constraints were not included when the effective web.xml was logged. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M1 through 10.1.55, from 9.0.0.M1 through 9.0.118, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected. Users are recommended to upgrade to version 11.0.23, 10.1.56 or 9.0.119 which fixes the issue.
Severe if exploited (CVSS 9.1), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 29th percentile
Impact if exploited
9.1CVSS 3.1 · CRITICAL
- 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: No special conditions — reliably repeatable
✓ 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-2026-55276/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-2026-55276/poc.json
Weakness (CWE)
- CWE-670: Always-Incorrect Control Flow Implementation
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Apache | Tomcat | < 9.0.119 |
| Apache | Tomcat | ≥ 10.1.0 and < 10.1.56 |
| Apache | Tomcat | ≥ 11.0.0 and < 11.0.23 |
All CVSS metrics
- CRITICAL 9.1 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - CRITICAL 9.1 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N