CVE-2022-21680Public exploitNetwork attack vector

Service interruption via reference-definition backtracking

Published Jan 14, 2022 · Updated Apr 22, 2025

ReDoS in Marked before 4.0.10 allows remote attackers to interrupt services by submitting crafted Markdown reference definitions. The block.def expression in src/rules.js applies nested, ambiguous whitespace repetitions while parsing a reference definition, causing catastrophic backtracking on long spaces around a title. Exposure requires untrusted Markdown to reach Marked without a worker time limit; exploitation consumes CPU and interrupts the hosting process or service.

CVSS severity7.5
High
EPSS probability2.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

ReDoS in Marked before 4.0.10 allows remote attackers to interrupt services by submitting crafted Markdown reference definitions. The block.def expression in src/rules.js applies nested, ambiguous whitespace repetitions while parsing a reference definition, causing catastrophic backtracking on long spaces around a title. Exposure requires untrusted Markdown to reach Marked without a worker time limit; exploitation consumes CPU and interrupts the hosting process or service.

The record

CVE
CVE-2022-21680
Published
Jan 14, 2022
Updated
Apr 22, 2025
Vendor
MarkedJS
Product
Marked
Classifications
CWE-1333, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.0.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MarkedJS · Markedversion=< 4.0.10

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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