CVE-2020-26133: An issue was discovered in Dual DHCP DNS Server 7.40

Routine

HIGH 7.8DOWNGRADE

CVE-2020-26133 is a high-severity flaw (CVSS 7.8) affecting dual dhcp dns server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Dual DHCP DNS Server 7.40. Due to insufficient access restrictions in the default installation directory, an attacker can elevate privileges by replacing the DualServer.exe binary.

Why this priority

High severity

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

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-732
Published	2020-10-28
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: dual dhcp dns server project

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

Am I affected?

Timeline

2020-10-28 18:15 UTCPublished CVE record published
2026-06-17 03:07 UTCUpdated Record last modified

dual dhcp dns server project dual dhcp dns server DOWNGRADE

Affected: 7.40

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.40

1. Check installed version

apt-cache policy dual-dhcp-dns-server || rpm -q dual-dhcp-dns-server || dual-dhcp-dns-server --version

2. No fixed release: DOWNGRADE to a release before 7.40 (Debian / Ubuntu)

apt-cache madison dual-dhcp-dns-server sudo apt install dual-dhcp-dns-server=<VERSION_BEFORE_7.40> sudo apt-mark hold dual-dhcp-dns-server

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

dnf --showduplicates list dual-dhcp-dns-server sudo dnf downgrade dual-dhcp-dns-server-<VERSION_BEFORE_7.40> sudo dnf versionlock add dual-dhcp-dns-server

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-2020-26133?

dual dhcp dns server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-26133 being exploited?

CVE-2020-26133 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-2020-26133 affect?

CVE-2020-26133 affects dual dhcp dns server. Severity is high (CVSS 7.8). An issue was discovered in Dual DHCP DNS Server 7.40. Due to insufficient access restrictions in the default installation directory, an attacker can elevate privileges by replacing the DualServer.exe binary.

How urgent is CVE-2020-26133?

Priority 34/100. High severity

References

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