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CVE-2026-59922

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:f79ba12577fd970ffc32de1b4bcd1672e929cbe0f988573db378d1a536316efe
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-1333","description":"CWE-1333: Inefficient Regular Expression Complexity","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

1 source assertion
{"product":"mistune","vendor":"lepture","versions":[{"status":"affected","version":"< 3.3.0"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-1333","description":"CWE-1333: Inefficient Regular Expression Complexity","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/problemTypes/1/descriptions/0

Source references

4 source assertions
{"name":"https://github.com/lepture/mistune/commit/96d0f57f8fe9eeb06bb4cff521962a27d7c402e7","tags":["x_refsource_MISC"],"url":"https://github.com/lepture/mistune/commit/96d0f57f8fe9eeb06bb4cff521962a27d7c402e7"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/references/1
{"name":"https://github.com/lepture/mistune/releases/tag/v3.3.0","tags":["x_refsource_MISC"],"url":"https://github.com/lepture/mistune/releases/tag/v3.3.0"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/references/2
{"name":"https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq","tags":["x_refsource_CONFIRM"],"url":"https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/cna/references/0
{"tags":["exploit"],"url":"https://github.com/lepture/mistune/security/advisories/GHSA-c8j7-8cv4-2xmq"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:3c1ff6db606432f7cc584a3add918afaef92a817525021e3b7a6a00a8cceb440 · sha256:4072409031056e39… · /containers/adp/0/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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