CVE-2020-6816

Name: CVE-2020-6816
Creator: NVD / NIST
Published: 2020-03-24T22:15:12.657+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 1.30%

Last modified Jun 17, 2026

CVE-2020-6816 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. 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.. EPSS estimates a 1.30% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.1/10

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

EPSS Probability

1.30%

66.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Mozilla	Bleach	< 3.1.2
Fedoraproject	Fedora	33

References

https://advisory.checkmarx.net/advisory/CX-2020-4277Exploit, Third Party Advisory
https://github.com/mozilla/bleach/security/advisories/GHSA-m6xf-fq7q-8743Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EDQU2SZLZMSSACCBUBJ6NOSRNNBDYFW5/
https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleachExploit, Third Party Advisory
https://advisory.checkmarx.net/advisory/CX-2020-4277Exploit, Third Party Advisory
https://github.com/mozilla/bleach/security/advisories/GHSA-m6xf-fq7q-8743Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EDQU2SZLZMSSACCBUBJ6NOSRNNBDYFW5/
https://www.checkmarx.com/blog/vulnerabilities-discovered-in-mozilla-bleachExploit, Third Party Advisory

Timeline

Published: Mar 24, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-6816?

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.

How severe is CVE-2020-6816?

CVE-2020-6816 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 1.30% probability of exploitation in the next 30 days.

How do I fix CVE-2020-6816?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-6816?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST