CVE-2021-36755: Nightscout Web Monitor (aka cgm-remote-monitor) 14.2.2 allows XSS via a crafted X-Forwarded-For header.

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-36755 is a medium-severity flaw (CVSS 6.1) affecting cgm-remote-monitor. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Nightscout Web Monitor (aka cgm-remote-monitor) 14.2.2 allows XSS via a crafted X-Forwarded-For header.

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	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-07-16
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cgm-remote-monitor project

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

Am I affected?

Timeline

2021-07-16 00:15 UTCPublished CVE record published
2026-06-17 03:59 UTCUpdated Record last modified

cgm-remote-monitor project cgm-remote-monitor DOWNGRADE

Affected: 14.2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 14.2.2

1. Check installed version

apt-cache policy cgm-remote-monitor || rpm -q cgm-remote-monitor || cgm-remote-monitor --version

2. No fixed release: DOWNGRADE to a release before 14.2.2 (Debian / Ubuntu)

apt-cache madison cgm-remote-monitor sudo apt install cgm-remote-monitor=<VERSION_BEFORE_14.2.2> sudo apt-mark hold cgm-remote-monitor

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

dnf --showduplicates list cgm-remote-monitor sudo dnf downgrade cgm-remote-monitor-<VERSION_BEFORE_14.2.2> sudo dnf versionlock add cgm-remote-monitor

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-2021-36755?

cgm-remote-monitor: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-36755 being exploited?

CVE-2021-36755 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-2021-36755 affect?

CVE-2021-36755 affects cgm-remote-monitor. Severity is medium (CVSS 6.1). Nightscout Web Monitor (aka cgm-remote-monitor) 14.2.2 allows XSS via a crafted X-Forwarded-For header.

How urgent is CVE-2021-36755?

Priority 34/100. No elevated risk signals yet.

References

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