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.
CVE-2020-26870
This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 4.9%, top 9% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.1
- EG Score
- 6.1(medium)
- EG Risk
- 34(Track)EG Risk 34/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity61% × 45%Exploitation5% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 91.1%
- KEV
- Not listed
Published
October 7, 2020
Last Modified
November 21, 2024
References (12)
- cve@mitrehttps://github.com/cure53/DOMPurify/commit/02724b8eb048dd219d6725b05c3000936f11d62d
- cve@mitrehttps://github.com/cure53/DOMPurify/compare/2.0.16...2.0.17
- cve@mitrehttps://lists.debian.org/debian-lts-announce/2020/10/msg00029.html
- cve@mitrehttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-26870
- cve@mitrehttps://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/
- cve@mitrehttps://www.oracle.com//security-alerts/cpujul2021.html
- af854a3a-2127-422b-91ae-364da2661108https://github.com/cure53/DOMPurify/commit/02724b8eb048dd219d6725b05c3000936f11d62d
- af854a3a-2127-422b-91ae-364da2661108https://github.com/cure53/DOMPurify/compare/2.0.16...2.0.17
- af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2020/10/msg00029.html
- af854a3a-2127-422b-91ae-364da2661108https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-26870
- af854a3a-2127-422b-91ae-364da2661108https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/
- af854a3a-2127-422b-91ae-364da2661108https://www.oracle.com//security-alerts/cpujul2021.html
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| dompurify | — | 2.0.17 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(1)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 12× in last 7d / 44× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 01:52 UTCEG score recompute
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- 2026-05-23 06:56 UTCVendor advisory
Related CVEs(same vendor + same CWE)
Same vendor
10 shownmsrc
- CVE-2006-10003EG 9.8CRITICAL
- CVE-2015-20107NVD 7.6EG 9.8EPSS 94%HIGH
- CVE-2013-7381EG 9.8CRITICAL
- CVE-2014-0048EG 9.8EPSS 93%CRITICAL
- CVE-2007-4559EG 9.8EPSS 98%CRITICAL
- CVE-2013-3900NVD 5.5EG 9.0 KEVEPSS 99%MEDIUM
- CVE-2013-2094NVD 8.4EG 9.0 KEVEPSS 99%HIGH
- CVE-2014-9356EG 8.6EPSS 91%HIGH
- CVE-2014-5282EG 8.1HIGH
- CVE-2014-8141EG 7.8EPSS 94%HIGH
Frequently asked(5)
What is CVE-2020-26870?
When was CVE-2020-26870 disclosed?
Is CVE-2020-26870 actively exploited?
What is the CVSS score of CVE-2020-26870?
How do I remediate CVE-2020-26870?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26870
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