CVE-2021-21306
Denial of Service in Marked
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Denial of Service in Marked
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.
- Record
CVE-2021-21306- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2021-0532
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.
- Record
EUVD-2021-0532- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-4r62-v4vq-hr96
Regular Expression Denial of Service (REDoS) in Marked
Impact
What kind of vulnerability is it? Who is impacted?
Regular expression Denial of Service
A Denial of Service attack can affect anyone who runs user generated code through marked.
Patches
Has the problem been patched? What versions should users upgrade to?
patched in v2.0.0
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
None.
References
Are there any links users can visit to find out more?
https://github.com/markedjs/marked/issues/1927 https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS
For more information
If you have any questions or comments about this advisory:
- Open an issue in marked
- Record
GHSA-4r62-v4vq-hr96- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-21306- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-400
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-21306- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVGHSA-4r62-v4vq-hr96
Regular Expression Denial of Service (REDoS) in Marked
Impact
What kind of vulnerability is it? Who is impacted?
Regular expression Denial of Service
A Denial of Service attack can affect anyone who runs user generated code through marked.
Patches
Has the problem been patched? What versions should users upgrade to?
patched in v2.0.0
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
None.
References
Are there any links users can visit to find out more?
https://github.com/markedjs/marked/issues/1927 https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS
For more information
If you have any questions or comments about this advisory:
- Open an issue in marked
- Record
GHSA-4r62-v4vq-hr96- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-400
- Updated
- 2026-11-02
OSVCLSA-2026-1784769550 No score
TuxCare security update for marked (3 CVEs)
TuxCare rebuilt marked to address 3 CVEs. Fixed in 1.2.7-tuxcare.1.
- Record
CLSA-2026-1784769550- Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21306 is a medium vulnerability (CVSS 5.3) in Marked Project Marked, published February 8, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.49%, the 84th percentile. Fixed in marked 2.0.0.
References
github.com/markedjs/marked/security/advisories/GHSA-4r62-v4vq-hr96
npmjs.com/package/marked
nvd.nist.gov/vuln/detail/CVE-2021-21306