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Fencer Intel
medium 6.1

CVE-2020-26870 json

Cross-site Scripting in dompurify

published 6y ago modified 4mo ago also GHSA-63q7-h895-m982 , EUVD-2020-1486

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.9%
EPSS 4.9% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

Cure53 DOMPurify before 2.0.17 allows mutation XSS. This occurs because a serialize-parse roundtrip does not necessarily return the original DOM tree, and a namespace can change from HTML to MathML, as demonstrated by nesting of FORM elements.

Patch / fix

  • npm dompurify 2.0.17
  • cure53 dompurify 2.0.17
  • oracle application_express 21.1.0.00.01

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Exploit prediction

4.88% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • research.securitum.com https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm dompurify
<2.0.17
2.0.17

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.