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CVE-2021-21366

17
FAUCET Score

CVE-2021-21366 affects xmldom versions 0.4.0 and older, a JavaScript XML DOM parser, and related Debian products. The vulnerability allows for unexpected syntactic changes during XML processing due to improper preservation of system identifiers, FPIs, or namespaces when repeatedly parsing and serializing maliciously crafted documents. Rated Medium (CVSS 4.3), this vulnerability requires user interaction (UI:R) and could lead to low impact on integrity (I:L), but does not affect confidentiality or availability. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.5.0CPE matchmatch criteria
cpe:2.3:a:xmldom_project:xmldom:*:*:*:*:*:node.js:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.33%
Probability of exploitation in next 30 days
EPSS Percentile
68.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0133 is in the 81st percentile among its peer group of 26,221 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 (2)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: xmldomFixed in: 0.5.0

Vendor Advisories (2)

redhatCVE-2021-21366Moderate

xmldom: incorrect parsing and serialization leads to unexpected behavior

Mar 12, 2023
npmGHSA-h6q6-9hqw-rwfvmedium

Misinterpretation of malicious XML input

Mar 12, 2021

References

github.com / xmldom/xmldom/commit/d4201b9dfbf760049f457f9f08a3888d48835135
Patch
github.com / xmldom/xmldom/releases/tag/0.5.0
Release Notes
github.com / xmldom/xmldom/security/advisories/GHSA-h6q6-9hqw-rwfv
Vendor Advisory
lists.debian.org / debian-lts-announce/2023/01/msg00000.html
Mailing ListThird Party Advisory
npmjs.com / package/xmldom
Product