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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.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:ed9c26247bd6a67d83b829e1813b7d050e213c4423506be12ed4502e4c84c175
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-1333","description":"CWE-1333: Inefficient Regular Expression Complexity","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/problemTypes/1/descriptions/0

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

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/problemTypes/0/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:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /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:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-1333","description":"CWE-1333: Inefficient Regular Expression Complexity","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/problemTypes/1/descriptions/0
{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/problemTypes/0/descriptions/0

Source references

4 source assertions
{"name":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69","tags":["x_refsource_MISC"],"url":"https://github.com/lepture/mistune/commit/2b04d7ba341c16ac78fe82d3076bdd5c3de87c69"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /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:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/references/2
{"name":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q","tags":["x_refsource_CONFIRM"],"url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /containers/cna/references/0
{"tags":["exploit"],"url":"https://github.com/lepture/mistune/security/advisories/GHSA-ffq3-xpv3-j92q"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:0439af2f4bc3567f3350b733f4512b9a301ff88f8a576a05e80399db0b893603 · sha256:03227d86a01625e1… · /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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