CVE-2020-6817: mozilla bleach
Vulnerability summary
CVE-2020-6817 is a high (CVSS 7.5) vulnerability in mozilla bleach. EPSS estimates a 0.72% chance of exploitation in the next 30 days, higher than 53.9% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (reference, Date unknown)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 5 · Related 5Timeline
- 16-02-2023PublishedVulnerability first disclosed.
- 19-03-2025Last modifiedVulnerability information updated.
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']}).
CVSS metrics
6 scores · 5 sources · 2 versions- OSV · PypiEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.72%
Chance of exploitation in the next 30 days
Percentile
54%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.72% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundExploit Reference (bugzilla.mozilla.org)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Mozilla2 products
- bleach< 3.1.4
- mozilla bleach≥ unspecified, < 3.1.4
Debian1 product
- python-bleach< 1.4-1+deb8u1 | < 3.1.4-1
PyPI1 product
- bleach< 3.1.4
Ubuntu1 product
- python-bleach< 1.4.2-1ubuntu0.1~esm1 | < 2.1.2-1ubuntu0.1~esm1 | < 3.1.1-1ubuntu0.1~esm1
4 vendors · 5 products
References
14 links
- github.com/mozilla/bleachPACKAGE
