How severe is CVE-2021-26271?

CVE-2021-26271 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-26271 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26271?

CVE-2021-26271 primarily affects Ckeditor. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26271?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-26271 published?

CVE-2021-26271 was published on 2021-01-26 and last updated on 2026-06-17.

CVE-2021-26271

CVE-2021-26271 is a medium-severity vulnerability in Ckeditor with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-829.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-829
Affected product: Ckeditor
Published: 2021-01-26
Last modified: 2026-06-17

Description

It was possible to execute a ReDoS-type attack inside CKEditor 4 before 4.16 by persuading a victim to paste crafted text into the Styles input of specific dialogs (in the Advanced Tab for Dialogs plugin).

Frequently asked questions

What is CVE-2021-26271?: It was possible to execute a ReDoS-type attack inside CKEditor 4 before 4.16 by persuading a victim to paste crafted text into the Styles input of specific dialogs (in the Advanced Tab for Dialogs plugin).
How severe is CVE-2021-26271?: CVE-2021-26271 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-26271 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26271?: CVE-2021-26271 primarily affects Ckeditor. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26271?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-26271 published?: CVE-2021-26271 was published on 2021-01-26 and last updated on 2026-06-17.

References

Affected products (11)

cpe:2.3:a:ckeditor:ckeditor:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:agile_plm:9.3.5:*:*:*:*:*:*:*
cpe:2.3:a:oracle:agile_plm:9.3.6:*:*:*:*:*:*:*
cpe:2.3:a:oracle:application_express:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:8.1.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:8.1.1:*:*:*:*:*:*:*
cpe:2.3:a:oracle:jd_edwards_enterpriseone_tools:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:siebel_ui_framework:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:webcenter_sites:12.2.1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:webcenter_sites:12.2.1.4.0:*:*:*:*:*:*:*

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