CVE-2020-28918: DualShield 5.9.8.0821 allows username enumeration on its login form

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MEDIUM 5.3REMOTEDOWNGRADE

CVE-2020-28918 is a medium-severity flaw (CVSS 5.3) affecting dualshield. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

DualShield 5.9.8.0821 allows username enumeration on its login form. A valid username results in prompting for the password, whereas an invalid one will produce an "unknown username" error message.

Why this priority

Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Published	2021-02-16
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: deepnetsecurity

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

Am I affected?

Timeline

2021-02-16 20:15 UTCPublished CVE record published
2026-06-17 03:10 UTCUpdated Record last modified

deepnetsecurity dualshield DOWNGRADE

Affected: 5.9.8.0821

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.9.8.0821

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.9.8.0821 (Debian / Ubuntu)

apt-cache madison dualshield sudo apt install dualshield=<VERSION_BEFORE_5.9.8.0821> sudo apt-mark hold dualshield

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

dnf --showduplicates list dualshield sudo dnf downgrade dualshield-<VERSION_BEFORE_5.9.8.0821> sudo dnf versionlock add dualshield

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-2020-28918?

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

Is CVE-2020-28918 being exploited?

CVE-2020-28918 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-2020-28918 affect?

CVE-2020-28918 affects dualshield. Severity is medium (CVSS 5.3). DualShield 5.9.8.0821 allows username enumeration on its login form. A valid username results in prompting for the password, whereas an invalid one will produce an "unknown username" error message.

How urgent is CVE-2020-28918?

Priority 40/100. Remotely exploitable, no login, no user action

References

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