CVE-2020-7869: An improper input validation vulnerability of ZOOK software (remote administration tool) could allow a remote

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CRITICAL 9.0DOWNGRADE

CVE-2020-7869 is a critical-severity flaw (CVSS 9.0) affecting zook. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An improper input validation vulnerability of ZOOK software (remote administration tool) could allow a remote attacker to create arbitrary file. The ZOOK viewer has the "Tight file CMD" function to create file. An attacker could create and execute arbitrary file in the ZOOK agent program using "Tight file CMD" without authority.

Why this priority

Critical severity

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

Risk facts

CVSS score	9.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-20
Published	2021-06-29
Last modified	2026-06-17

Publisher (CNA): KrCERT/CC · Vendor: mastersoft

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

Am I affected?

Timeline

2021-06-29 14:15 UTCPublished CVE record published
2026-06-17 03:25 UTCUpdated Record last modified

mastersoft zook DOWNGRADE

Affected: 2.0.4.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.4.6

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0.4.6 (Debian / Ubuntu)

apt-cache madison zook sudo apt install zook=<VERSION_BEFORE_2.0.4.6> sudo apt-mark hold zook

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

dnf --showduplicates list zook sudo dnf downgrade zook-<VERSION_BEFORE_2.0.4.6> sudo dnf versionlock add zook

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-2020-7869?

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

Is CVE-2020-7869 being exploited?

CVE-2020-7869 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-2020-7869 affect?

CVE-2020-7869 affects zook. Severity is critical (CVSS 9.0). An improper input validation vulnerability of ZOOK software (remote administration tool) could allow a remote attacker to create arbitrary file. The ZOOK viewer has the "Tight file CMD" function to create file. An attacker could create and

How urgent is CVE-2020-7869?

Priority 51/100. Critical severity

References

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