Cyber Resilience

CVE-2026-59083

Apache Tomcat ≤ 8.0.0

Published
14 July 2026
Modified
14 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.0037 30th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-59083 is a critical-severity Hex Encoding (CWE-177) vulnerability in Apache Tomcat. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 30th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Improper 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…

more

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.

CWE(s)
CWE-177

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Direct security constraint bypass in public-facing Tomcat rewrite valve enables exploitation of the web application (T1190).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

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CVE-2025-66614Same product: Apache Tomcat
CVE-2026-34486Same product: Apache Tomcat
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CVE-2026-29146Same product: Apache Tomcat

Affected Assets

apache
tomcat
≤ 8.0.0 · 8.5.0 — 8.5.100 · 9.0.0 — 9.0.119

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • SI-10 Information Input Validation
  • SC-7 Boundary Protection
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces the security constraints that the URL-encoding flaw in the rewrite valve is bypassing.

SI-10 Information Input Validation good match
prevent

Requires validation and canonicalization of URL inputs to block hex-encoding bypasses before constraint evaluation.

SC-7 Boundary Protection partial match
prevent

Boundary-protection mechanisms (e.g., WAF rules) can inspect and drop malformed or encoded requests targeting the rewrite valve.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require correct URL-encoding/decoding and input validation during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
detects

Security testing in development catches URL-decoding flaws before release, but does not itself define coding rules.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC processes include validation steps that reduce CWE-177, yet the control is broader than this single weakness.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for input validation and canonicalization, directly preventing improper URL decoding.

A.8.28 Secure coding partial match
prevents

Secure coding standards mandate proper handling and decoding of encoded inputs, eliminating CWE-177.

References