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CVE-2021-32808

Cross-site scripting in ckeditor via abuse of undo functionality

7.6 HighFix available

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
Low
Availability
None

Exploit likelihood

1.19%Up 0.6 points since Aug 13, 2021
90%50%10%1%

What each source reports

CVE List Score used 7.6

Cross-site scripting in ckeditor via abuse of undo functionality

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
CVE-2021-32808
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
EUVDEUVD-2021-1585 7.6

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
EUVD-2021-1585
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-6226-h7ff-ch6c 7.6

Widget feature vulnerability allowing to execute JavaScript code using undo functionality

Affected packages

The vulnerability has been discovered in Widget plugin if used alongside Undo feature.

Impact

A potential vulnerability has been discovered in CKEditor 4 Widget package. The vulnerability allowed to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0.

Patches

The problem has been recognized and patched. The fix will be available in version 4.16.2.

For more information

Email us at [email protected] if you have any questions or comments about this advisory.

Acknowledgements

The CKEditor 4 team would like to thank Anton Subbotin (skavans) for recognizing and reporting this vulnerability.

Record
GHSA-6226-h7ff-ch6c
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
NVD 7.6

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
CVE-2021-32808
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
3.5 LowAV:N/AC:M/Au:S/C:N/I:P/A:N
Weakness
CWE-79
Updated
2026-11-02
OSV 5.4

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
CVE-2021-32808
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-32808 5.4

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
DEBIAN-CVE-2021-32808
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-6226-h7ff-ch6c 7.6

Widget feature vulnerability allowing to execute JavaScript code using undo functionality

Affected packages

The vulnerability has been discovered in Widget plugin if used alongside Undo feature.

Impact

A potential vulnerability has been discovered in CKEditor 4 Widget package. The vulnerability allowed to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0.

Patches

The problem has been recognized and patched. The fix will be available in version 4.16.2.

For more information

Email us at [email protected] if you have any questions or comments about this advisory.

Acknowledgements

The CKEditor 4 team would like to thank Anton Subbotin (skavans) for recognizing and reporting this vulnerability.

Record
GHSA-6226-h7ff-ch6c
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSVUBUNTU-CVE-2021-32808 5.4

ckeditor is an open source WYSIWYG HTML editor with rich content support. A vulnerability has been discovered in the clipboard Widget plugin if used alongside the undo feature. The vulnerability allows a user to abuse undo functionality using malformed widget HTML, which could result in executing JavaScript code. It affects all users using the CKEditor 4 plugins listed above at version >= 4.13.0. The problem has been recognized and patched. The fix will be available in version 4.16.2.

Record
UBUNTU-CVE-2021-32808
CVSS 3.1
5.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CVSS 3.1
7.6 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N
Updated
2026-11-02
OSVUSN-5340-1 No score

ckeditor vulnerabilities

Kyaw Min Thein discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to execute arbitrary code. This issue only affects Ubuntu 18.04 LTS. (CVE-2018-9861)

Micha Bentkowski discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to execute arbitrary code. This issue only affects Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2020-9281)

Anton Subbotin discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to execute arbitrary code. This issue only affects Ubuntu 21.10. (CVE-2021-32808)

Anton Subbotin discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to inject arbitrary code. (CVE-2021-32809)

Or Sahar discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to execute arbitrary code. This issue only affects Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2021-33829)

Mika Kulmala discovered that CKEditor incorrectly handled certain inputs. An attacker could possibly use this issue to execute arbitrary code. (CVE-2021-37695)

Record
USN-5340-1
Updated
2026-11-02

Affected products

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Affected packages

Affected packages
PackageAffectedFixed
ckeditor4
npm
4.13.0 up to 4.16.2
4.16.2
ckeditor
Debian:12
before 4.16.2+dfsg-1
4.16.2+dfsg-1
ckeditor
Ubuntu:18.04:LTS
From an advisory covering 6 CVEs
before 4.5.7+dfsg-2ubuntu0.18.04.1, plus listed versions
4.5.7+dfsg-2
4.5.7+dfsg-2ubuntu0.18.04.1
ckeditor
Ubuntu:20.04:LTS
From an advisory covering 6 CVEs
before 4.12.1+dfsg-1ubuntu0.1, plus listed versions
4.11.1+dfsg-14.12.1+dfsg-1
4.12.1+dfsg-1ubuntu0.1

History

History
RecordedChangedSources
affected, facts
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-32808 is a high vulnerability (CVSS 7.6) in Ckeditor, published August 12, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.19%, the 68th percentile. Fixed in ckeditor4 4.16.2.

References

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