CVE-2020-21861: File upload vulnerability in DuxCMS 2.1 allows attackers to execute arbitrary php code via duxcms/AdminUpload/

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HIGH 8.8DOWNGRADE

CVE-2020-21861 is a high-severity flaw (CVSS 8.8) affecting duxcms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

File upload vulnerability in DuxCMS 2.1 allows attackers to execute arbitrary php code via duxcms/AdminUpload/upload.

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	Low
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-434
Published	2023-07-06
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: duxcms project

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

Am I affected?

Timeline

2023-07-06 14:15 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

duxcms project duxcms DOWNGRADE

Affected: 2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.1 (Debian / Ubuntu)

apt-cache madison duxcms sudo apt install duxcms=<VERSION_BEFORE_2.1> sudo apt-mark hold duxcms

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

dnf --showduplicates list duxcms sudo dnf downgrade duxcms-<VERSION_BEFORE_2.1> sudo dnf versionlock add duxcms

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-2020-21861?

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

Is CVE-2020-21861 being exploited?

CVE-2020-21861 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-2020-21861 affect?

CVE-2020-21861 affects duxcms. Severity is high (CVSS 8.8). File upload vulnerability in DuxCMS 2.1 allows attackers to execute arbitrary php code via duxcms/AdminUpload/upload.

How urgent is CVE-2020-21861?

Priority 49/100. High severity; Public exploit reference

Software pages

PHP vulnerabilities

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References

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