Cyber Resilience

CVE-2026-4509

Published
21 March 2026
Modified
24 April 2026
CVSS Score v4 5.3
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0029 21th percentile
Risk Priority 32 floored blend · peak EPSS

Summary

CVE-2026-4509 is a medium-severity Permissive List of Allowed Inputs (CWE-183) vulnerability. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 21th 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 SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

A security flaw has been discovered in PbootCMS up to 3.2.12. This affects an unknown function of the file core/function/file.php of the component File Upload. The manipulation of the argument black results in incomplete blacklist. The attack may be launched…

more

remotely. The exploit has been released to the public and may be used for attacks.

CWE(s)
CWE-183CWE-184

Related Threats

MITRE ATT&CK Enterprise Techniques

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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-15625Shared CWE-183, CWE-184
CVE-2026-16129Shared CWE-183, CWE-184
CVE-2026-59802Shared CWE-183
CVE-2026-48557Shared CWE-184
CVE-2026-41392Shared CWE-184
CVE-2026-44115Shared CWE-184
CVE-2026-11525Shared CWE-183
CVE-2026-42435Shared CWE-184
CVE-2026-53861Shared CWE-184
CVE-2023-45593Shared CWE-184

Affected Assets

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)
  • V1.5.2
  • V4.4.2
  • V3.5.2
  • V16.2.5

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Strict validity checks on inputs directly stop overly permissive allow lists from being used as the protection mechanism.

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 rigorous allow-list design and testing that prevents permissive input validation.

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
finds

Security testing can detect overly broad allow-lists, but does not inherently prevent their creation.

A.8.26 Application security requirements partial match
prevents

Application security requirements can mandate strict, minimal allow-lists and input validation rules that prevent overly permissive lists.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles require explicit, least-privilege input validation designs that directly address permissive allow-lists.

A.8.28 Secure coding partial match
prevents

Secure coding standards enforce rigorous input validation and reject unsafe values, mitigating permissive allow-list weaknesses.

A.8.9 Configuration management none match
none

Configuration management can enforce validated input rules, yet does not directly address the design flaw of permissive lists.

References