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CVE-2021-39199

22
FAUCET Score

CVE-2021-39199 is a cross-site scripting (XSS) vulnerability affecting the remark-html Node.js library, which compiles Markdown to HTML. Previously, the library's default configuration did not sanitize user input, allowing arbitrary HTML to be passed through. This medium-severity vulnerability (CVSS 6.1) has a low attack complexity and can lead to information disclosure and integrity issues if a user interacts with a malicious link. There is no evidence of active exploitation, nor is public exploit code available, though it has garnered significant community discussion. Patches in versions 13.0.2 and 14.0.1 now make remark-html safe by default, aligning with its documentation.

Impacted Technologies

VendorProductVersion(s)CPE
< 13.0.2CPE matchmatch criteria
cpe:2.3:a:remark:remark-html:*:*:*:*:*:node.js:*:*
>= 14.0.0, < 14.0.1CPE matchmatch criteria
cpe:2.3:a:remark:remark-html:*:*:*:*:*:node.js:*:*

CVSS Data

CVSS version used by this source: 3.1

10.0CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.8
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.07%
Probability of exploitation in next 30 days
EPSS Percentile
61.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0107 is in the 74th percentile among its peer group of 26,236 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: remark-htmlFixed in: 13.0.2
npmpatch availablevia ghsa
Product: remark-htmlFixed in: 14.0.1

Vendor Advisories (1)

npmGHSA-9q5w-79cv-947mcritical

Unsafe defaults in `remark-html`

Sep 7, 2021

References

github.com / remarkjs/remark-html/commit/b75c9dde582ad87ba498e369c033dc8a350478c1
PatchThird Party Advisory
github.com / remarkjs/remark-html/releases/tag/14.0.1
PatchRelease NotesThird Party Advisory
github.com / remarkjs/remark-html/security/advisories/GHSA-9q5w-79cv-947m
PatchThird Party Advisory
npmjs.com / package/remark-html
ProductThird Party Advisory