How severe is CVE-2021-21306?

CVE-2021-21306 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-21306 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21306?

CVE-2021-21306 affects Marked Project Marked. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21306?

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

When was CVE-2021-21306 published?

CVE-2021-21306 was published on 2021-02-08 and last updated on 2026-06-17.

CVE-2021-21306

CVE-2021-21306 is a medium-severity vulnerability in Marked Project Marked with a CVSS 3.x base score of 5.3. 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-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 2% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Marked Project Marked
Published: 2021-02-08
Last modified: 2026-06-17

Description

Marked is an open-source markdown parser and compiler (npm package "marked"). In marked from version 1.1.1 and before version 2.0.0, there is a Regular expression Denial of Service vulnerability. This vulnerability can affect anyone who runs user generated code through marked. This vulnerability is fixed in version 2.0.0.

Frequently asked questions

What is CVE-2021-21306?: Marked is an open-source markdown parser and compiler (npm package "marked"). In marked from version 1.1.1 and before version 2.0.0, there is a Regular expression Denial of Service vulnerability. This vulnerability can affect anyone who runs user generated code through marked. This vulnerability is fixed in version 2.0.0.
How severe is CVE-2021-21306?: CVE-2021-21306 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-21306 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21306?: CVE-2021-21306 affects Marked Project Marked. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21306?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-21306 published?: CVE-2021-21306 was published on 2021-02-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:marked_project:marked:*:*:*:*:*:node.js:*:*

More vulnerabilities in Marked Project Marked

CVE-2026-41680 — High (CVSS 7.5): Marked is a markdown parser and compiler. From 18.0.0 to 18.0.1, a critical Denial of Service (DoS) vulnerability…
CVE-2018-25110 — High (CVSS 7.5): Marked prior to version 0.3.17 is vulnerable to a Regular Expression Denial of Service (ReDoS) attack due to…
CVE-2022-21681 — High (CVSS 7.5): Marked is a markdown parser and compiler. Prior to version 4.0.10, the regular expression `inline.reflinkSearch` may…
CVE-2022-21680 — High (CVSS 7.5): Marked is a markdown parser and compiler. Prior to version 4.0.10, the regular expression `block.def` may cause…
CVE-2017-16114 — High (CVSS 7.5): The marked module is vulnerable to a regular expression denial of service. Based on the information published in the…
CVE-2015-8854 — High (CVSS 7.5): The marked package before 0.3.4 for Node.js allows attackers to cause a denial of service (CPU consumption) via…

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