CVE-2020-18890: Rmote Code Execution (RCE) vulnerability in puppyCMS v5.1 due to insecure permissions, which could let a remot

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2020-18890 is a critical-severity flaw (CVSS 9.8) affecting puppycms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Rmote Code Execution (RCE) vulnerability in puppyCMS v5.1 due to insecure permissions, which could let a remote malicious user getshell via /admin/functions.php.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Weakness	CWE-281
Published	2021-05-06
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: puppycms

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

Am I affected?

Timeline

2021-05-06 18:15 UTCPublished CVE record published
2026-06-17 02:59 UTCUpdated Record last modified

puppycms puppycms DOWNGRADE

Affected: 5.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.1 (Debian / Ubuntu)

apt-cache madison puppycms sudo apt install puppycms=<VERSION_BEFORE_5.1> sudo apt-mark hold puppycms

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

dnf --showduplicates list puppycms sudo dnf downgrade puppycms-<VERSION_BEFORE_5.1> sudo dnf versionlock add puppycms

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-2020-18890?

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

Is CVE-2020-18890 being exploited?

CVE-2020-18890 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-2020-18890 affect?

CVE-2020-18890 affects puppycms. Severity is critical (CVSS 9.8). Rmote Code Execution (RCE) vulnerability in puppyCMS v5.1 due to insecure permissions, which could let a remote malicious user getshell via /admin/functions.php.

How urgent is CVE-2020-18890?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2022-3464 MEDIUM 4.3 UPGRADE A vulnerability classified as problematic has been found in puppyCMS up to 5.1
CVE-2020-18889 MEDIUM 6.5 DOWNGRADE Cross Site Request Forgery (CSRF) vulnerability in puppyCMS v5.1 that can change the admin's password via /adm
CVE-2020-18888 HIGH 7.5 DOWNGRADE Arbitrary File Deletion vulnerability in puppyCMS v5.1 allows remote malicious attackers to delete the file/fo

References

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