CVE-2023-22486Public exploitNetwork attack vector

Service interruption via quadratic opener-list traversal

Published Jan 24, 2023 · Updated Mar 10, 2025

Inefficient algorithmic complexity in GitHub cmark-gfm before 0.29.0.gfm.7 allows attackers to exhaust CPU via crafted Markdown. In handle_close_bracket, the is_image logic repeatedly walks the opener list to its beginning for each repeated ![ sequence, producing quadratic parsing time. Any application that parses attacker-controlled Markdown can hang or become unavailable while processing a sufficiently large document.

CVSS severity7.5
High
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Inefficient algorithmic complexity in GitHub cmark-gfm before 0.29.0.gfm.7 allows attackers to exhaust CPU via crafted Markdown. In handle_close_bracket, the is_image logic repeatedly walks the opener list to its beginning for each repeated ![ sequence, producing quadratic parsing time. Any application that parses attacker-controlled Markdown can hang or become unavailable while processing a sufficiently large document.

The record

CVE
CVE-2023-22486
Published
Jan 24, 2023
Updated
Mar 10, 2025
Vendor
Twitter
Product
cmark-gfm
Classifications
CWE-400, CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 24, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

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

Published CVSS scores

7.5NISTCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-407Inefficient Algorithmic Complexity
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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