CVE-2020-5631: Stored cross-site scripting vulnerability in CMONOS.JP ver2.0.20191009 and earlier allows remote attackers to

Routine

MEDIUM 6.1DOWNGRADE

CVE-2020-5631 is a medium-severity flaw (CVSS 6.1) affecting cmonos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stored cross-site scripting vulnerability in CMONOS.JP ver2.0.20191009 and earlier allows remote attackers to inject 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	1.0% (top 36%)
CISA exploited list	No
Weakness	CWE-79
Published	2020-10-06
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: cmonos

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

Am I affected?

Timeline

2020-10-06 06:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

cmonos cmonos DOWNGRADE

Affected: 2.0.20200916

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.20200916

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0.20200916 (Debian / Ubuntu)

apt-cache madison cmonos sudo apt install cmonos=<VERSION_BEFORE_2.0.20200916> sudo apt-mark hold cmonos

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

dnf --showduplicates list cmonos sudo dnf downgrade cmonos-<VERSION_BEFORE_2.0.20200916> sudo dnf versionlock add cmonos

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-2020-5631?

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

Is CVE-2020-5631 being exploited?

CVE-2020-5631 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-2020-5631 affect?

CVE-2020-5631 affects cmonos. Severity is medium (CVSS 6.1). Stored cross-site scripting vulnerability in CMONOS.JP ver2.0.20191009 and earlier allows remote attackers to inject arbitrary script via unspecified vectors.

How urgent is CVE-2020-5631?

Priority 37/100. No elevated risk signals yet.

References

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