CVE-2021-39199: remark-html is an open source nodejs library which compiles Markdown to HTML

Q: How do I fix CVE-2021-39199?

remark-html: upgrade to 13.0.2, 14.0.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-39199 being exploited?

CVE-2021-39199 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-39199 affect?

CVE-2021-39199 affects remark-html. Severity is critical (CVSS 10.0). remark-html is an open source nodejs library which compiles Markdown to HTML. In affected versions the documentation of remark-html has mentioned that it was safe by default. In practice the default was never safe and had to be opted into.

Q: How urgent is CVE-2021-39199?

Priority 56/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 10.0REMOTEUPGRADE

CVE-2021-39199 is a critical-severity flaw (CVSS 10.0) affecting remark-html. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

remark-html is an open source nodejs library which compiles Markdown to HTML. In affected versions the documentation of remark-html has mentioned that it was safe by default. In practice the default was never safe and had to be opted into. That is, user input was not sanitized. This means arbitrary HTML can be passed through leading to potential XSS attacks. The problem has been patched in 13.0.2 and 14.0.1: `remark-html` is now safe by default,

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-09-07
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: remark

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

Am I affected?

Timeline

2021-09-07 19:15 UTCPublished CVE record published
2026-06-17 04:03 UTCUpdated Record last modified

remark remark-html UPGRADE

Affected: < 13.0.2 · >= 14.0.0 and < 14.0.1

Fixed in: 13.0.2, 14.0.1

Safe to downgrade to: a release before 14.0.0

1. Check installed version

npm ls remark-html

2. UPGRADE to 13.0.2

npm install remark-html@">=13.0.2"

3. If no update is available yet, DOWNGRADE to a release before 14.0.0

npm view remark-html versions npm install remark-html@"<14.0.0"

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-2021-39199?

remark-html: upgrade to 13.0.2, 14.0.1. Exact commands for each OS are on this page.

Is CVE-2021-39199 being exploited?

CVE-2021-39199 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-2021-39199 affect?

CVE-2021-39199 affects remark-html. Severity is critical (CVSS 10.0). remark-html is an open source nodejs library which compiles Markdown to HTML. In affected versions the documentation of remark-html has mentioned that it was safe by default. In practice the default was never safe and had to be opted into.

How urgent is CVE-2021-39199?

Priority 56/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

References

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