CVE-2021-47870: GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-47870 is a medium-severity flaw (CVSS 5.4) affecting getsimplecms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability. The plugin attempts to sanitize user input using htmlspecialchars(), but this can be bypassed by passing dangerous characters as escaped hex bytes. This allows attackers to inject arbitrary client-side code that executes in the administrator's browser when visiting a malicious page.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-01-21
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: get-simple

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

Am I affected?

Timeline

2026-01-21 18:16 UTCPublished CVE record published
2026-06-17 04:18 UTCUpdated Record last modified

get-simple getsimplecms DOWNGRADE

Affected: 1.1.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.1.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.1.2 (Debian / Ubuntu)

apt-cache madison getsimplecms sudo apt install getsimplecms=<VERSION_BEFORE_1.1.2> sudo apt-mark hold getsimplecms

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

dnf --showduplicates list getsimplecms sudo dnf downgrade getsimplecms-<VERSION_BEFORE_1.1.2> sudo dnf versionlock add getsimplecms

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-2021-47870?

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

Is CVE-2021-47870 being exploited?

CVE-2021-47870 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-2021-47870 affect?

CVE-2021-47870 affects getsimplecms. Severity is medium (CVSS 5.4). GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability. The plugin attempts to sanitize user input using htmlspecialchars(), but this can be bypassed by passing dangerous characters as esca

How urgent is CVE-2021-47870?

Priority 29/100. Public exploit reference

Related CVEs

CVE-2024-11125 MEDIUM 4.3 DOWNGRADE A vulnerability was found in GetSimpleCMS 3.3.16 and classified as problematic
CVE-2021-47860 MEDIUM 5.3 DOWNGRADE GetSimple CMS Custom JS 0.1 plugin contains a cross-site request forgery vulnerability that allows unauthentic
CVE-2021-47830 MEDIUM 6.5 DOWNGRADE GetSimple CMS My SMTP Contact Plugin 1.1.1 contains a cross-site request forgery (CSRF) vulnerability
CVE-2021-47778 HIGH 7.2 DOWNGRADE GetSimple CMS My SMTP Contact Plugin 1.1.2 contains a PHP code injection vulnerability
CVE-2013-10032 HIGH 8.8 DOWNGRADE An authenticated remote code execution vulnerability exists in GetSimpleCMS version 3.2.1

References

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