CVE-2026-59930

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable toc_N values without slugifying the heading text, allowing attacker-controlled id="toc_N" content to collide with generated anchors and redirect same-page navigation, CSS selectors, or JavaScript handlers. This issue is fixed in version 3.3.0.

CVSS v3 4.3 MEDIUM

4.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b	Patch
https://github.com/lepture/mistune/releases/tag/v3.3.0	Release Notes
https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9	Exploit Third Party Advisory
https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9	Exploit Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-07-08 17:17

Updated : 2026-07-09 19:28

NVD link : CVE-2026-59930

Mitre link : CVE-2026-59930

CVE.ORG link : CVE-2026-59930

JSON object : View

Products Affected

mistune_project

mistune

CWE

CWE-345

Insufficient Verification of Data Authenticity

CWE-1284

Improper Validation of Specified Quantity in Input

{"id": "CVE-2026-59930", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-59930", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-09T13:53:53.247241Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 2.8}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "lepture", "product": "mistune", "versions": [{"status": "affected", "version": "< 3.3.0"}]}]}], "published": "2026-07-08T17:17:28.867", "references": [{"url": "https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/lepture/mistune/releases/tag/v3.3.0", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9", "tags": ["Exploit", "Third Party Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9", "tags": ["Exploit", "Third Party Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-345"}, {"lang": "en", "value": "CWE-1284"}]}], "descriptions": [{"lang": "en", "value": "Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the toc plugin and TableOfContents directive generate heading IDs as predictable toc_N values without slugifying the heading text, allowing attacker-controlled id=\"toc_N\" content to collide with generated anchors and redirect same-page navigation, CSS selectors, or JavaScript handlers. This issue is fixed in version 3.3.0."}], "lastModified": "2026-07-09T19:28:30.570", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "63E1B933-D2E2-44EF-A56C-94483300845B", "versionEndExcluding": "3.3.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}