CVE-2026-31272: MRCMS 3.1.2 contains an access control vulnerability

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2026-31272 is a critical-severity flaw (CVSS 9.8) affecting mrcms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-284
Published	2026-04-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mrcms

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-07 18:16 UTCPublished CVE record published
2026-06-17 10:33 UTCUpdated Record last modified

mrcms mrcms DOWNGRADE

Affected: 3.1.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1.2

1. Check installed version

apt-cache policy mrcms || rpm -q mrcms || mrcms --version

2. No fixed release: DOWNGRADE to a release before 3.1.2 (Debian / Ubuntu)

apt-cache madison mrcms sudo apt install mrcms=<VERSION_BEFORE_3.1.2> sudo apt-mark hold mrcms

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mrcms sudo dnf downgrade mrcms-<VERSION_BEFORE_3.1.2> sudo dnf versionlock add mrcms

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · python-googleapis-common-protos · FIXED · 1.75.5-1.fc46~bootstrap · FEDORA-2026-d911c4c4e6 · source

sudo dnf upgrade --advisory=FEDORA-2026-d911c4c4e6

Fedora ELN · see advisory · FIXED · FEDORA-2026-e3987c278f · source

sudo dnf upgrade --advisory=FEDORA-2026-e3987c278f

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/clockw1se0v0/Vul/blob/main/MRCMS/Unauthorized.md

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31272?

mrcms: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-31272 being exploited?

CVE-2026-31272 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31272 affect?

CVE-2026-31272 affects mrcms. Severity is critical (CVSS 9.8). 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 with

How urgent is CVE-2026-31272?

Priority 59/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

Related CVEs

CVE-2026-29909 MEDIUM 5.3 DOWNGRADE MRCMS V3.1.2 contains an unauthenticated directory enumeration vulnerability in the file management module

References

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