CVE-2020-23622: An issue in the UPnP protocol in 4thline cling 2.0.0 through 2.1.2 allows remote attackers to cause a denial o

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HIGH 7.5REMOTEUPGRADE

CVE-2020-23622 is a high-severity flaw (CVSS 7.5) affecting cling. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue in the UPnP protocol in 4thline cling 2.0.0 through 2.1.2 allows remote attackers to cause a denial of service via an unchecked CALLBACK parameter in the request header

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-918
Published	2022-08-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cling project

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

Am I affected?

Timeline

2022-08-15 20:15 UTCPublished CVE record published
2026-06-17 03:04 UTCUpdated Record last modified

cling project cling UPGRADE

Affected: >= 2.0.0 and <= 2.1.2

Fixed in: newer than 2.1.2

Safe to downgrade to: a release before 2.0.0

1. Check installed version

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

2. UPGRADE to newer than 2.1.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade cling

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cling

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison cling sudo apt install cling=<VERSION_BEFORE_2.0.0> sudo apt-mark hold cling

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list cling sudo dnf downgrade cling-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add cling

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-2020-23622?

cling: upgrade to newer than 2.1.2. Exact commands for each OS are on this page.

Is CVE-2020-23622 being exploited?

CVE-2020-23622 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-2020-23622 affect?

CVE-2020-23622 affects cling. Severity is high (CVSS 7.5). An issue in the UPnP protocol in 4thline cling 2.0.0 through 2.1.2 allows remote attackers to cause a denial of service via an unchecked CALLBACK parameter in the request header

How urgent is CVE-2020-23622?

Priority 53/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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