CVE catalog

CVE-2020-6817

python-bleach affected and fixed versions

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']}).

Severity: High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: Mar 26, 2020, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.72% · Oct 27, 2026

Projects and upstream resources

[python-bleach][Source-reported homepage]

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Distribution / release	Package	Version	Status	Source
Debiantrixie	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debiantrixie	python-bleach	`6.2.0-1`	Fixed	[CVE-2020-6817]
Debiansid	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debiansid	python-bleach	`6.3.0-1`	Fixed	[CVE-2020-6817]
Debianforky	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debianforky	python-bleach	`6.3.0-1`	Fixed	[CVE-2020-6817]
Debianbookworm	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debianbookworm	python-bleach	`5.0.1-2`	Fixed	[CVE-2020-6817]

Showing 8 fix observations. All 12 observations, including unknown and conflicting reports, are available below.

Provider details and historical evidence

Distribution / release	Package	Version	Status	Source
Debianbookworm	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debianbookworm	python-bleach	`5.0.1-2`	Fixed	[CVE-2020-6817]
Debianforky	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debianforky	python-bleach	`6.3.0-1`	Fixed	[CVE-2020-6817]
Debiansid	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debiansid	python-bleach	`6.3.0-1`	Fixed	[CVE-2020-6817]
Debiantrixie	python-bleach	`3.1.4-1`	FixedDistribution-reported fixed boundary	[CVE-2020-6817]
Debiantrixie	python-bleach	`6.2.0-1`	Fixed	[CVE-2020-6817]
Ubuntupro	python-bleach	`3.1.0-1`	UnknownSource applicability is not established	[UBUNTU-CVE-2020-6817]Mar 9, 2026, 11:19:21 AM UTC
Ubuntupro	python-bleach	`3.1.0-2`	UnknownSource applicability is not established	[UBUNTU-CVE-2020-6817]Mar 9, 2026, 11:19:21 AM UTC
Ubuntupro	python-bleach	`3.1.1-1`	UnknownSource applicability is not established	[UBUNTU-CVE-2020-6817]Mar 9, 2026, 11:19:21 AM UTC
Ubuntupro	python-bleach	`3.1.1-1ubuntu0.1~esm1`	UnknownSource applicability is not established	[UBUNTU-CVE-2020-6817]Mar 9, 2026, 11:19:21 AM UTC

Original provider fields

{
  "package_releases": [
    {
      "name": "python-bleach",
      "status": "fixed",
      "release": "sid",
      "version": "6.3.0-1"
    },
    {
      "name": "python-bleach",
      "status": "fixed",
      "release": "forky",
      "version": "6.3.0-1"
    },
    {
      "name": "python-bleach",
      "status": "fixed",
      "release": "trixie",
      "version": "6.2.0-1"
    },
    {
      "name": "python-bleach",
      "status": "fixed",
      "release": "bookworm",
      "version": "5.0.1-2"
    }
  ],
  "fixed_versions": [
    {
      "bug": 955388,
      "name": "python-bleach",
      "type": "source",
      "origin": null,
      "release": "sid",
      "urgency": "not yet assigned",
      "fixed_version": "3.1.4-1"
    },
    {
      "bug": 955388,
      "name": "python-bleach",
      "type": "source",
      "origin": null,
      "release": "forky",
      "urgency": "not yet assigned",
      "fixed_version": "3.1.4-1"
    },
    {
      "bug": 955388,
      "name": "python-bleach",
      "type": "source",
      "origin": null,
      "release": "trixie",
      "urgency": "not yet assigned",
      "fixed_version": "3.1.4-1"
    },
    {
      "bug": 955388,
      "name": "python-bleach",
      "type": "source",
      "origin": null,
      "release": "bookworm",
      "urgency": "not yet assigned",
      "fixed_version": "3.1.4-1"
    }
  ],
  "distribution_packages": [
    {
      "name": "python-bleach",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.1-1ubuntu0.1~esm1"
            }
          ]
        }
      ],
      "release": "pro",
      "versions": [
        "3.1.0-1",
        "3.1.0-2",
        "3.1.1-1"
      ],
      "ecosystem": "deb",
      "provider_url": "https://osv.dev/vulnerability/UBUNTU-CVE-2020-6817",
      "fixed_version": "3.1.1-1ubuntu0.1~esm1",
      "provider_source": "pypi",
      "provider_record_id": "UBUNTU-CVE-2020-6817",
      "provider_updated_at": "2026-03-09T11:19:21.037504Z",
      "applicability_unknown": true
    }
  ]
}

[Debian bug #955388]

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[python3-bleach]Unknown
Source package: [python-bleach]
Details (2)
- 5.0.1-2 · all · bookworm
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · bookworm; dsa · python-bleach · debian · 12
- 5.0.1-2 · all · bookworm
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · bookworm; dsa · python-bleach · debian · 12
[python-bleach-doc]Unknown
Source package: [python-bleach]
Details (2)
- 5.0.1-2 · all · bookworm
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · bookworm; dsa · python-bleach · debian · 12
- 5.0.1-2 · all · bookworm
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · bookworm; dsa · python-bleach · debian · 12

[Debian 13 (Trixie)]

[python3-bleach]Unknown
Source package: [python-bleach]
Details (2)
- 6.2.0-1 · all · trixie
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · 13
- 6.2.0-1 · all · trixie
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · 13
[python-bleach-doc]Unknown
Source package: [python-bleach]
Details (2)
- 6.2.0-1 · all · trixie
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · 13
- 6.2.0-1 · all · trixie
  Fixed · Fixed: 3.1.4-1
  dsa · python-bleach · debian · 13

Observed: Oct 23, 2026, 5:53:11 PM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]