CVE-2020-23837: A Cross-Site Request Forgery (CSRF) vulnerability in the Multi User plugin 1.8.2 for GetSimple CMS allows remo

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HIGH 8.8DOWNGRADE

CVE-2020-23837 is a high-severity flaw (CVSS 8.8) affecting multi user. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Cross-Site Request Forgery (CSRF) vulnerability in the Multi User plugin 1.8.2 for GetSimple CMS allows remote attackers to add admin (or other) users after an authenticated admin visits a third-party site or clicks on a URL.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-352
Published	2020-09-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: multi user project

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

Am I affected?

Timeline

2020-09-25 04:23 UTCPublished CVE record published
2026-06-17 03:05 UTCUpdated Record last modified

multi user project multi user DOWNGRADE

Affected: 1.8.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.8.2

1. Check installed version

apt-cache policy multi-user || rpm -q multi-user || multi-user --version

2. No fixed release: DOWNGRADE to a release before 1.8.2 (Debian / Ubuntu)

apt-cache madison multi-user sudo apt install multi-user=<VERSION_BEFORE_1.8.2> sudo apt-mark hold multi-user

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

dnf --showduplicates list multi-user sudo dnf downgrade multi-user-<VERSION_BEFORE_1.8.2> sudo dnf versionlock add multi-user

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.

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-2020-23837?

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

Is CVE-2020-23837 being exploited?

CVE-2020-23837 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-2020-23837 affect?

CVE-2020-23837 affects multi user. Severity is high (CVSS 8.8). A Cross-Site Request Forgery (CSRF) vulnerability in the Multi User plugin 1.8.2 for GetSimple CMS allows remote attackers to add admin (or other) users after an authenticated admin visits a third-party site or clicks on a URL.

How urgent is CVE-2020-23837?

Priority 50/100. High severity; Public exploit reference

References

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