CVE-2023-22484Public exploit

Denial of service via repeated HTML-comment scanning

Published Jan 23, 2023 · Updated Mar 10, 2025

Algorithmic complexity in GitHub cmark-gfm before 0.29.0.gfm.7 allows attackers to interrupt Markdown parsing with crafted input. The handle_pointy_brace path repeatedly invokes the scan_html_comment regular-expression scanner after each less-than sign in long <!-- sequences, producing quadratic work. Exposure requires an application or command-line workflow to parse attacker-controlled Markdown; a sufficiently large document can exhaust CPU and stall the parser or its hosting service.

CVSS severity3.5
Low
EPSS probability0.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity in GitHub cmark-gfm before 0.29.0.gfm.7 allows attackers to interrupt Markdown parsing with crafted input. The handle_pointy_brace path repeatedly invokes the scan_html_comment regular-expression scanner after each less-than sign in long <!-- sequences, producing quadratic work. Exposure requires an application or command-line workflow to parse attacker-controlled Markdown; a sufficiently large document can exhaust CPU and stall the parser or its hosting service.

The record

CVE
CVE-2023-22484
Published
Jan 23, 2023
Updated
Mar 10, 2025
Vendor
Twitter
Product
cmark-gfm
Classifications
CWE-407, CWE-400, T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Jan 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=< 0.29.0.gfm.7

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Twitter · cmark-gfmversion=< 0.29.0.gfm.7

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.5GitHub, Inc.CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-407Inefficient Algorithmic Complexity
CWE-400Uncontrolled Resource Consumption
T1499.004Application 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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