CVE-2021-41165 | HTML comments vulnerability allowing to execute JavaScript code

CKEditor4 is an open source WYSIWYG HTML editor. In affected version a vulnerability has been discovered in the core HTML processing module and may affect all plugins used by CKEditor 4. The vulnerability allowed to inject malformed comments 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.

Published: 2021-11-17 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-41165 is rated Moderate Risk (58.7/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.47%). EPSS rose +1.35% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-41165

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.12% 1.47% +1.35%
2 2025-12-24 0.16% 0.12% -0.04%
3 2025-12-20 — 0.16% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-41165

CVSS metrics for this CVE.

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]

Weakness enumeration for CVE-2021-41165

GitHub Security Advisory for CVE-2021-41165

GHSA-7h26-63m7-qhf2 · Severity: high · Ecosystem: npm — HTML comments vulnerability allowing to execute JavaScript code

OS Trackers for CVE-2021-41165

vendor priority summary link
debian not yet assigned CVE-2021-41165 not yet assigned priority: Debian including 2 source packages (ckeditor, ckeditor3), 4 status rows across 2 suites (bookworm, bullseye): open 3, resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-41165
ubuntu medium CVE-2021-41165 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-2021-41165

Affected software / configurations for CVE-2021-41165

Vendor Product Version Raw CPE
ckeditor ckeditor < 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 agile_product_lifecycle_management 9.3.6 cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.6:*:*:*:*:*:*:*
oracle application_express < 22.1 cpe:2.3:a:oracle:application_express:*:*:*:*:*:*:*:*
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 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:*:*:*:*:*:*:*

References for CVE-2021-41165

cvelogic Threat Intelligence