Vulnerability Details CVE-2026-59928
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many repeated or distinct reference-link definitions causes quadratic work in src/mistune/block_parser.py and the ref_links environment dictionary handling, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 28.7%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-59928
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cpe:2.3:a:mistune_project:mistune:0.1.0
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cpe:2.3:a:mistune_project:mistune:0.2.0
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cpe:2.3:a:mistune_project:mistune:0.3.0
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cpe:2.3:a:mistune_project:mistune:0.3.1
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cpe:2.3:a:mistune_project:mistune:0.4
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cpe:2.3:a:mistune_project:mistune:0.4.1
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cpe:2.3:a:mistune_project:mistune:0.5
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cpe:2.3:a:mistune_project:mistune:0.5.1
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cpe:2.3:a:mistune_project:mistune:0.6
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cpe:2.3:a:mistune_project:mistune:0.7
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cpe:2.3:a:mistune_project:mistune:0.7.1
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cpe:2.3:a:mistune_project:mistune:0.7.2
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cpe:2.3:a:mistune_project:mistune:0.7.3
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cpe:2.3:a:mistune_project:mistune:0.7.4
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cpe:2.3:a:mistune_project:mistune:0.8
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cpe:2.3:a:mistune_project:mistune:0.8.1
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cpe:2.3:a:mistune_project:mistune:0.8.2
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cpe:2.3:a:mistune_project:mistune:0.8.3
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cpe:2.3:a:mistune_project:mistune:0.8.4
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cpe:2.3:a:mistune_project:mistune:2.0.0
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cpe:2.3:a:mistune_project:mistune:2.0.1
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cpe:2.3:a:mistune_project:mistune:2.0.2
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cpe:2.3:a:mistune_project:mistune:2.0.3
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cpe:2.3:a:mistune_project:mistune:2.0.4
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cpe:2.3:a:mistune_project:mistune:2.0.5
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cpe:2.3:a:mistune_project:mistune:3.0.0
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cpe:2.3:a:mistune_project:mistune:3.0.1
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cpe:2.3:a:mistune_project:mistune:3.0.2
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cpe:2.3:a:mistune_project:mistune:3.1.0
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cpe:2.3:a:mistune_project:mistune:3.1.1
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cpe:2.3:a:mistune_project:mistune:3.1.2
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cpe:2.3:a:mistune_project:mistune:3.1.3
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cpe:2.3:a:mistune_project:mistune:3.1.4
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cpe:2.3:a:mistune_project:mistune:3.2.0
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cpe:2.3:a:mistune_project:mistune:3.2.1