CVE-2026-59930
Mistune toc / TableOfContents directive: heading IDs use predictable `toc_N` numbering with no slugification, allowing collision with attacker-controlled `id="toc_N"` content
Description
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.
INFO
Published Date :
July 8, 2026, 5:17 p.m.
Last Modified :
July 9, 2026, 7:28 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Mistune to version 3.3.0.
- Ensure heading IDs are properly slugified.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-59930.
| URL | 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 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-59930 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-59930
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-59930 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-59930 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 09, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:* versions up to (excluding) 3.3.0 Added Reference Type GitHub, Inc.: https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b Types: Patch Added Reference Type GitHub, Inc.: https://github.com/lepture/mistune/releases/tag/v3.3.0 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9 Types: Exploit, Third Party Advisory Added Reference Type CISA-ADP: https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9 Types: Exploit, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 09, 2026
Action Type Old Value New Value Added Reference https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9 Added SSVC {'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'} -
New CVE Received by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'lepture', 'product': 'mistune', 'versions': [{'status': 'affected', 'version': '< 3.3.0'}]}] Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N Added CWE CWE-345 Added CWE CWE-1284 Added Reference https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b Added Reference https://github.com/lepture/mistune/releases/tag/v3.3.0 Added Reference https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9