CVE-2026-31272

CriticalPublic PoC

Published: 07 April 2026

Published

07 April 2026

Modified

14 April 2026

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0007 20.2th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-31272 is a critical-severity Improper Access Control (CWE-284) vulnerability in Mrcms Mrcms. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 20.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 AC-2 (Account Management) and AC-3 (Access Enforcement).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 3 other techniques. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

AC-3 Access Enforcement good match

prevent

Enforces approved authorizations for logical access to system resources, directly addressing the lack of authorization validation in the UserController save() method that allows unauthenticated super administrator creation.

AC-2 Account Management good match

prevent

Requires approval and controlled procedures for creating and managing system accounts, preventing unauthorized addition of super administrator accounts.

AC-6 Least Privilege good match

prevent

Employs least privilege to restrict access and privileges, mitigating the impact of unauthorized super administrator account creation by limiting excessive permissions.

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 →

T1136 Create Account Persistence

Adversaries may create an account to maintain access to victim systems.

attack.mitre.org →

T1136.001 Local Account Persistence

Adversaries may create a local account to maintain access to victim systems.

attack.mitre.org →

T1078 Valid Accounts Stealth

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.

attack.mitre.org →

Why these techniques?

Direct unauthenticated remote creation of super-admin accounts in public-facing MRCMS enables T1190 (exploit public-facing app for initial access), T1136/T1136.001 (create local account), and subsequent T1078 (valid accounts abuse).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

MRCMS 3.1.2 contains an access control vulnerability. The save() method in src/main/java/org/marker/mushroom/controller/UserController.java lacks proper authorization validation, enabling direct addition of super administrator accounts without authentication.

Deeper analysisAI

CVE-2026-31272 is an access control vulnerability (CWE-284) affecting MRCMS version 3.1.2. The issue resides in the save() method of the UserController class at src/main/java/org/marker/mushroom/controller/UserController.java, which lacks proper authorization validation. This flaw enables unauthenticated users to directly add super administrator accounts.

The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), marking it as critical. Remote attackers with no required privileges or user interaction can exploit it over the network with low complexity. Successful exploitation allows creation of super administrator accounts, resulting in high-impact compromise of confidentiality, integrity, and availability.

Mitigation details are available in the referenced advisory at https://github.com/clockw1se0v0/Vul/blob/main/MRCMS/Unauthorized.md, published on 2026-04-07.