CVE-2021-32536: The login page in the MCUsystem does not filter with special characters, which allows remote attackers can inj

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-32536 is a medium-severity flaw (CVSS 6.1) affecting mcusystem. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The login page in the MCUsystem does not filter with special characters, which allows remote attackers can inject JavaScript without privilege and thus perform reflected XSS attacks.

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	2021-06-18
Last modified	2026-06-17

Publisher (CNA): TWCERT/CC · Vendor: mcusystem

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

Am I affected?

Timeline

2021-06-18 10:15 UTCPublished CVE record published
2026-06-17 03:53 UTCUpdated Record last modified

mcusystem mcusystem DOWNGRADE

Affected: 5.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.5

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.5 (Debian / Ubuntu)

apt-cache madison mcusystem sudo apt install mcusystem=<VERSION_BEFORE_5.5> sudo apt-mark hold mcusystem

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

dnf --showduplicates list mcusystem sudo dnf downgrade mcusystem-<VERSION_BEFORE_5.5> sudo dnf versionlock add mcusystem

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-2021-32536?

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

Is CVE-2021-32536 being exploited?

CVE-2021-32536 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-2021-32536 affect?

CVE-2021-32536 affects mcusystem. Severity is medium (CVSS 6.1). The login page in the MCUsystem does not filter with special characters, which allows remote attackers can inject JavaScript without privilege and thus perform reflected XSS attacks.

How urgent is CVE-2021-32536?

Priority 35/100. No elevated risk signals yet.

References

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