CVE-2021-39393: mm-wiki v0.2.1 was discovered to contain a cross-site scripting (XSS) vulnerability via the markdown editor.

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-39393 is a medium-severity flaw (CVSS 6.1) affecting mm-wiki. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

mm-wiki v0.2.1 was discovered to contain a cross-site scripting (XSS) vulnerability via the markdown editor.

Why this priority

Public exploit reference

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	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-08-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mm-wiki project

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

Am I affected?

Timeline

2022-08-26 13:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

mm-wiki project mm-wiki DOWNGRADE

Affected: 0.2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.2.1

1. Check installed version

apt-cache policy mm-wiki || rpm -q mm-wiki || mm-wiki --version

2. No fixed release: DOWNGRADE to a release before 0.2.1 (Debian / Ubuntu)

apt-cache madison mm-wiki sudo apt install mm-wiki=<VERSION_BEFORE_0.2.1> sudo apt-mark hold mm-wiki

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

dnf --showduplicates list mm-wiki sudo dnf downgrade mm-wiki-<VERSION_BEFORE_0.2.1> sudo dnf versionlock add mm-wiki

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-2021-39393?

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

Is CVE-2021-39393 being exploited?

CVE-2021-39393 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-2021-39393 affect?

CVE-2021-39393 affects mm-wiki. Severity is medium (CVSS 6.1). mm-wiki v0.2.1 was discovered to contain a cross-site scripting (XSS) vulnerability via the markdown editor.

How urgent is CVE-2021-39393?

Priority 38/100. Public exploit reference

Related CVEs

CVE-2021-39394 MEDIUM 6.5 DOWNGRADE mm-wiki v0.2.1 was discovered to contain a Cross-Site Request Forgery (CSRF) which allows attackers to arbitra
CVE-2020-19278 HIGH 8.8 DOWNGRADE Cross Site Request Forgery vulnerability found in Phachon mm-wiki v.0.1.2 allows a remote attacker to execute
CVE-2020-19277 MEDIUM 5.4 DOWNGRADE Cross Site Scripting vulnerability found in Phachon mm-wiki v.0.1.2 allows a remote attacker to execute arbitr

References

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