CVE-2021-20688: Cross-site scripting vulnerability in Click Ranker Ver.3.5 allows remote attackers to inject an arbitrary scri

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-20688 is a medium-severity flaw (CVSS 6.1) affecting click ranker. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross-site scripting vulnerability in Click Ranker Ver.3.5 allows remote attackers to inject an arbitrary script via unspecified vectors.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 44%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-04-07
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: click-ranker

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

Am I affected?

Timeline

2021-04-07 08:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

click-ranker click ranker DOWNGRADE

Affected: 3.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.5

1. Check installed version

apt-cache policy click-ranker || rpm -q click-ranker || click-ranker --version

2. No fixed release: DOWNGRADE to a release before 3.5 (Debian / Ubuntu)

apt-cache madison click-ranker sudo apt install click-ranker=<VERSION_BEFORE_3.5> sudo apt-mark hold click-ranker

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

dnf --showduplicates list click-ranker sudo dnf downgrade click-ranker-<VERSION_BEFORE_3.5> sudo dnf versionlock add click-ranker

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-2021-20688?

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

Is CVE-2021-20688 being exploited?

CVE-2021-20688 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-2021-20688 affect?

CVE-2021-20688 affects click ranker. Severity is medium (CVSS 6.1). Cross-site scripting vulnerability in Click Ranker Ver.3.5 allows remote attackers to inject an arbitrary script via unspecified vectors.

How urgent is CVE-2021-20688?

Priority 35/100. No elevated risk signals yet.

References

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