CVE-2020-6816

MEDIUMNVD 6.16.1—

6.1

In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCDATA and either svg or math tags are whitelisted and the keyword argument strip=False.

CVSS v3: 6.1
EG Score: 6.1(medium)
EPSS: 62.0%
KEV: Not listed

Published

March 24, 2020

Last Modified

November 21, 2024

References (8)

security@mozillahttps://advisory.checkmarx.net/advisory/CX-2020-4277
security@mozillahttps://github.com/mozilla/bleach/security/advisories/GHSA-m6xf-fq7q-8743
security@mozillahttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EDQU2SZLZMSSACCBUBJ6NOSRNNBDYFW5/
security@mozillahttps://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach
af854a3a-2127-422b-91ae-364da2661108https://advisory.checkmarx.net/advisory/CX-2020-4277
af854a3a-2127-422b-91ae-364da2661108https://github.com/mozilla/bleach/security/advisories/GHSA-m6xf-fq7q-8743
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EDQU2SZLZMSSACCBUBJ6NOSRNNBDYFW5/
af854a3a-2127-422b-91ae-364da2661108https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleach

Affected Packages

(1 across 1 ecosystem)

PyPI(1)

Package	Vulnerable range	Fixed in	Dependents
bleach	0.1 ... 3.1.1 (42 versions)	3.1.2	—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-79Cross-site Scripting (XSS)

Data Freshness Timeline

(refreshed 7× in last 7d / 7× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 05:55 UTCEG score recompute
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2020-6816?

CVE-2020-6816 is a medium vulnerability published on March 24, 2020. In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCDATA and either svg or math tags are whitelisted and the keyword argument strip=False.

When was CVE-2020-6816 disclosed?

CVE-2020-6816 was first published in the National Vulnerability Database on March 24, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2020-6816 actively exploited?

CVE-2020-6816 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 62.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2020-6816?

CVE-2020-6816 has a CVSS v3 base score of 6.1 (NVD).

How do I remediate CVE-2020-6816?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-6816, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-6816

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