Is CVE-2021-21254 in the CISA KEV catalog?

No. CVE-2021-21254 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-21254?

CVE-2021-21254 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2021-21254?

CVE-2021-21254 has an EPSS score of 1.79% (76th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21254?

Upgrade ckeditor5 to 25.0.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-21254

MEDIUMEPSS 76th pctl

6.5

CVSS v3

NVD

Description

CKEditor 5 is an open source rich text editor framework with a modular architecture. The CKEditor 5 Markdown plugin (@ckeditor/ckeditor5-markdown-gfm) before version 25.0.0 has a regex denial of service (ReDoS) vulnerability. The vulnerability allowed to abuse link recognition regular expression, which could cause a significant performance drop resulting in browser tab freeze. It affects all users using CKEditor 5 Markdown plugin at version <= 24.0.0. The problem has been recognized and patched. The fix will be available in version 25.0.0.

CWE-400Resource Exhaustion

How to fix

Remediation Available

ckeditor5NVD

Affected:< 25.0.0Fixed in:25.0.0CVE-2021-21254derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

1.79%probability of exploitation in 30 days

76thpercentile

Elevated risk: more likely to be exploited than 76% of all known CVEs.

References

Third-Party Advisory2

Other references1

npmjs.com

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-44487	High	7.5	100%	KEV	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2011-3192	High	7.8	99%	-	Fix
CVE-2019-11478	Medium	5.3	95%	-	Fix
CVE-2024-25617	Medium	5.3	89%	-	Fix
CVE-2018-1000115	High	7.5	89%	-	Fix

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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.