CVE-2020-6817
CVE-2020-6817 is a high-severity vulnerability in Mozilla Bleach with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1333.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 1% (49th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-1333
- Affected product: Mozilla Bleach
- Published:
- Last modified:
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']}).
Frequently asked questions
- What is CVE-2020-6817?
- 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']}).
- How severe is CVE-2020-6817?
- CVE-2020-6817 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2020-6817 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2020-6817?
- CVE-2020-6817 affects Mozilla Bleach. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2020-6817?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2020-6817 published?
- CVE-2020-6817 was published on 2023-02-16 and last updated on 2026-06-17.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1623633
- https://github.com/mozilla/bleach/security/advisories/GHSA-vqhp-cxgc-6wmm
Affected products (1)
- cpe:2.3:a:mozilla:bleach:*:*:*:*:*:*:*:*
More vulnerabilities in Mozilla Bleach
- CVE-2018-7753 — Critical (CVSS 9.8): An issue was discovered in Bleach 2.1.x before 2.1.3. Attributes that have URI values weren't properly sanitized if the…
- CVE-2021-23980 — Medium (CVSS 6.1): A mutation XSS affects users calling bleach.clean with all of: svg or math in the allowed tags p or br in allowed tags…
- CVE-2020-6816 — Medium (CVSS 6.1): In Mozilla Bleach before 3.12, a mutation XSS in bleach.clean when RCDATA and either svg or math tags are whitelisted…
- CVE-2020-6802 — Medium (CVSS 6.1): In Mozilla Bleach before 3.11, a mutation XSS affects users calling bleach.clean with noscript and a raw tag in the…
All CVEs affecting Mozilla Bleach →
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