CVE-2020-25494: Xinuos (formerly SCO) Openserver v5 and v6 allows attackers to execute arbitrary commands via shell metacharac

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2020-25494 is a critical-severity flaw (CVSS 9.8) affecting openserver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Xinuos (formerly SCO) Openserver v5 and v6 allows attackers to execute arbitrary commands via shell metacharacters in outputform or toclevels parameter to cgi-bin/printbook.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
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	39.2% (top 1%)
CISA exploited list	No
Weakness	CWE-78
Published	2020-12-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: xinuos

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

Am I affected?

Timeline

2020-12-18 15:15 UTCPublished CVE record published
2026-06-17 03:06 UTCUpdated Record last modified

xinuos openserver DOWNGRADE

Affected: 5.0.7 · 6.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.0.7 (Debian / Ubuntu)

apt-cache madison openserver sudo apt install openserver=<VERSION_BEFORE_5.0.7> sudo apt-mark hold openserver

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

dnf --showduplicates list openserver sudo dnf downgrade openserver-<VERSION_BEFORE_5.0.7> sudo dnf versionlock add openserver

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.

Public exploits and detection

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

Exploit-DB: SCO Openserver 5.0.7 - 'outputform' Command Injection

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-2020-25494?

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

Is CVE-2020-25494 being exploited?

CVE-2020-25494 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-2020-25494 affect?

CVE-2020-25494 affects openserver. Severity is critical (CVSS 9.8). Xinuos (formerly SCO) Openserver v5 and v6 allows attackers to execute arbitrary commands via shell metacharacters in outputform or toclevels parameter to cgi-bin/printbook.

How urgent is CVE-2020-25494?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-25495 MEDIUM 6.1 DOWNGRADE A reflected Cross-site scripting (XSS) vulnerability in Xinuo (formerly SCO) Openserver version 5 and 6 allows

References

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