What’s Vulnerable › Vulnerabilities

CVE-2020-6817

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-02-16 · updated 2026-06-17
• Weakness: CWE-1333

Description

bleach.clean behavior parsing style attributes could result in a regular expression denial of service (ReDoS). Calls to bleach.clean with an allowed tag with an allowed style attribute are vulnerable to ReDoS. For example, bleach.clean(..., attributes={'a': ['style']}).

Affected products

• Mozilla Bleach: before 3.1.4 — fixed in 3.1.4

How to fix

Upgrade to a fixed version: Mozilla Bleach 3.1.4. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1623633
• https://github.com/mozilla/bleach/security/advisories/GHSA-vqhp-cxgc-6wmm
• https://bugzilla.mozilla.org/show_bug.cgi?id=1623633
• https://github.com/mozilla/bleach/security/advisories/GHSA-vqhp-cxgc-6wmm

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