CVE-2023-22483Public exploit

Denial of service via quadratic Markdown parsing

Published Jan 23, 2023 · Updated Mar 10, 2025

Algorithmic complexity flaws in GitHub cmark-gfm before 0.29.0.gfm.7 allow attackers to interrupt parsing with crafted Markdown. Ten parsing paths, including handle_pointy_brace, process_emphasis, table row parsing, and autolink matching, repeatedly rescan or grow output quadratically on adversarial character patterns. Any application or command that passes untrusted Markdown to an affected parser can consume excessive CPU or memory, and one reference-link case can crash the process.

CVSS severity3.5
Low
EPSS probability1.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity flaws in GitHub cmark-gfm before 0.29.0.gfm.7 allow attackers to interrupt parsing with crafted Markdown. Ten parsing paths, including handle_pointy_brace, process_emphasis, table row parsing, and autolink matching, repeatedly rescan or grow output quadratically on adversarial character patterns. Any application or command that passes untrusted Markdown to an affected parser can consume excessive CPU or memory, and one reference-link case can crash the process.

The record

CVE
CVE-2023-22483
Published
Jan 23, 2023
Updated
Mar 10, 2025
Vendor
Twitter
Product
cmark-gfm
Classifications
CWE-407, CWE-400, T1499.004
Attack vector
adjacent
Privileges
authenticated

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 vectoradjacent
Required privilegesauthenticated

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
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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