CVE-2026-59083
CRITICAL 9.1 ALL-YEARSImproper Handling of URL Encoding (Hex Encoding) vulnerability in Apache Tomcat's rewrite valve allowed security constraint bypass for some configurations. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.23, from 10.1.0-M1 through 10.1.56, from 9.0.0.M1 through 9.0.119, 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 11.0.24, 10.1.57 or 9.0.120, which fix the issue.
Severe if exploited (CVSS 9.1), but no confirmed exploitation. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 30th percentile
Impact if exploited
9.1CVSS 3.1 · CRITICAL · ADP
- 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
No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.
Weakness (CWE)
- CWE-177: Improper Handling of URL Encoding (Hex Encoding)
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 | ≤ 8.0.0 |
| Apache | Tomcat | ≥ 8.5.0 and ≤ 8.5.100 |
| Apache | Tomcat | ≥ 9.0.0 and ≤ 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