CVE-2020-6816

Exp

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.

Published: 2020-03-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

NVD Status：Modified，CVE State: published

View at NVD, CVE.org, EUVD

Threat Intelligence & Risk Assessment for CVE-2020-6816

EPSS CVSS CWE GHSA Exploit-DB Affected OS Tracker

Conclusion & alert: CVE-2020-6816 is rated High Exploit Risk (63.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.30%). Core evidence: 2 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2020-6816

EDB-ID	Source	Kind	Published	Link
—	nvd_ref	exploit_tag		Exploit-DB ↗
—	nvd_ref	exploit_tag		Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-6816

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.42%	1.30%	+0.88%
2	2025-11-21	0.34%	0.42%	+0.08%
3	2025-11-18	—	0.34%	—

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-6816

CVSS metrics for this CVE.

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.1	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.8	2.7	[email protected]
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	8.6	2.9	[email protected]

Weakness enumeration for CVE-2020-6816

CWE-79 MITRE ↗

GitHub Security Advisory for CVE-2020-6816

GHSA-m6xf-fq7q-8743 · Severity: medium · Ecosystem: pip — Bleach vulnerable to mutation XSS via whitelisted math or svg and raw tag

OS Trackers for CVE-2020-6816

vendor	priority	summary	link
`alpine`	medium	CVE-2020-6816: 1 source package rows (py3-bleach); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0.	https://security.alpinelinux.org/vuln/CVE-2020-6816
`debian`	not yet assigned	CVE-2020-6816 not yet assigned priority: Debian including 1 source packages (python-bleach), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2020-6816
`ubuntu`	medium	CVE-2020-6816 medium priority: Ubuntu including 1 source packages (python-bleach), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 11, released 4, DNE 1, ignored 1.	https://ubuntu.com/security/CVE-2020-6816

Affected software / configurations for CVE-2020-6816

Vendor	Product	Version	Raw CPE
mozilla	bleach	< 3.1.2	cpe:2.3:a:mozilla:bleach::::::::
fedoraproject	fedora	33	cpe:2.3:o:fedoraproject:fedora:33:::::::*

References for CVE-2020-6816

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

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