CVE-2021-41164 [High] | XSS in Ckeditor

CKEditor4 is an open source WYSIWYG HTML editor. In affected versions a vulnerability has been discovered in the Advanced Content Filter (ACF) module and may affect all plugins used by CKEditor 4. The vulnerability allowed to inject malformed HTML bypassing content sanitization, which could result in executing JavaScript code. It affects all users using the CKEditor 4 at version < 4.17.0. The problem has been recognized and patched. The fix will be available in version 4.17.0.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.08%	1.26%	+1.18%
2	2025-12-24	0.18%	0.08%	-0.10%
3	2025-12-23	—	0.18%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.08%

1.26%

+1.18%

2025-12-24

0.18%

0.08%

-0.10%

2025-12-23

—

0.18%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.2	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.3	5.3	[email protected]
5.4	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.3	2.7	[email protected]
3.5	2.0	LOW	`AV:N/AC:M/Au:S/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	6.8	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.2

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.3

5.3

[email protected]

5.4

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.3

2.7

[email protected]

3.5

2.0

LOW

AV:N/AC:M/Au:S/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

6.8

2.9

[email protected]

OS Trackers for CVE-2021-41164

vendor	priority	summary	link
`debian`	unimportant	CVE-2021-41164 unimportant priority: Debian including 2 source packages (ckeditor, ckeditor3), 4 status rows across 2 suites (bookworm, bullseye): resolved 3, open 1.	https://security-tracker.debian.org/tracker/CVE-2021-41164
`ubuntu`	medium	CVE-2021-41164 medium priority: Ubuntu including 4 source packages (ckeditor, ckeditor3, ldap-account-manager, request-tracker4), 60 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 36, needs-triage 12, not-affected 6, DNE 5, released 1.	https://ubuntu.com/security/CVE-2021-41164

Affected software / configurations for CVE-2021-41164

Vendor	Product	Version	Raw CPE
ckeditor	ckeditor	>= 4.0, < 4.17.0	cpe:2.3:a:ckeditor:ckeditor::::::::
drupal	drupal	>= 8.9.0, < 8.9.20	cpe:2.3:a:drupal:drupal::::::::
drupal	drupal	>= 9.1.0, < 9.1.14	cpe:2.3:a:drupal:drupal::::::::
drupal	drupal	>= 9.2.0, < 9.2.9	cpe:2.3:a:drupal:drupal::::::::
oracle	banking_apis	>= 18.1, <= 18.3	cpe:2.3:a:oracle:banking_apis::::::::
oracle	banking_apis	19.1	cpe:2.3:a:oracle:banking_apis:19.1:::::::*
oracle	banking_apis	19.2	cpe:2.3:a:oracle:banking_apis:19.2:::::::*
oracle	banking_apis	20.1	cpe:2.3:a:oracle:banking_apis:20.1:::::::*
oracle	banking_apis	21.1	cpe:2.3:a:oracle:banking_apis:21.1:::::::*
oracle	banking_digital_experience	>= 18.1, <= 18.3	cpe:2.3:a:oracle:banking_digital_experience::::::::
oracle	banking_digital_experience	19.1	cpe:2.3:a:oracle:banking_digital_experience:19.1:::::::*
oracle	banking_digital_experience	19.2	cpe:2.3:a:oracle:banking_digital_experience:19.2:::::::*
oracle	banking_digital_experience	20.1	cpe:2.3:a:oracle:banking_digital_experience:20.1:::::::*
oracle	banking_digital_experience	21.1	cpe:2.3:a:oracle:banking_digital_experience:21.1:::::::*
oracle	agile_plm	9.3.6	cpe:2.3:a:oracle:agile_plm:9.3.6:::::::*
oracle	application_express	< 22.1	cpe:2.3:a:oracle:application_express::::::::
oracle	commerce_guided_search	11.3.2	cpe:2.3:a:oracle:commerce_guided_search:11.3.2:::::::*
oracle	peoplesoft_enterprise_peopletools	8.58	cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.58:::::::*
oracle	peoplesoft_enterprise_peopletools	8.59	cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.59:::::::*
oracle	webcenter_portal	12.2.1.3.0	cpe:2.3:a:oracle:webcenter_portal:12.2.1.3.0:::::::*
oracle	webcenter_portal	12.2.1.4.0	cpe:2.3:a:oracle:webcenter_portal:12.2.1.4.0:::::::*
fedoraproject	fedora	36	cpe:2.3:o:fedoraproject:fedora:36:::::::*
fedoraproject	fedora	37	cpe:2.3:o:fedoraproject:fedora:37:::::::*

References for CVE-2021-41164

URL	Tags
https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-417	Patch Third Party Advisory
https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-pvmx-g8h5-cprj	Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VR76VBN5GW5QUBJFHVXRX36UZ6YTCMW6/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WOZGMCYDB2OKKULFXZKM6V7JJW4ZZHJP/
https://www.drupal.org/sa-core-2021-011	Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html	Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html	Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html	Not Applicable

URL

CVE-2021-41164 | Advanced Content Filter (ACF) vulnerability allowing to execute JavaScript code using malformed HTML

Exploit prediction scoring system (EPSS) score for CVE-2021-41164

Common vulnerability scoring system (CVSS) metrics for CVE-2021-41164

Weakness enumeration for CVE-2021-41164

GitHub Security Advisory for CVE-2021-41164

OS Trackers for CVE-2021-41164

Affected software / configurations for CVE-2021-41164

References for CVE-2021-41164