Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-07-08T16:13:21 mistune: Mistune: Same-page navigation redirection due to predictable heading IDs 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N CWE-79

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.

A flaw was found in Mistune, a Python Markdown parser. The table of contents (toc) plugin and TableOfContents directive generate heading identifiers (IDs) as predictable values (e.g., toc_N) without properly processing the heading text. This allows an attacker to control content with a colliding ID, which can redirect same-page navigation, CSS selectors, or JavaScript handlers. This could lead to unexpected behavior or information disclosure within the application.

This flaw has a Moderate impact on Red Hat products that ship mistune 3.x with the toc plugin. Exploitation requires the attacker to submit Markdown content to a multi-author rendering context where toc is enabled, limiting the practical attack surface. Red Hat products shipping mistune 0.8.x are not affected because the toc plugin is a 3.x-only feature. There are no known mitigations for this issue. Migration Toolkit for Applications 8 Fix deferred mta/mta-solution-server-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-pipeline-runtime-tensorflow-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-pipeline-runtime-tensorflow-rocm-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-th06-cpu-torch210-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-th06-cpu-torch291-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-th06-cuda130-torch210-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-th06-cuda130-torch291-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-th06-rocm64-torch291-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-datascience-cpu-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Fix deferred rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-tensorflow-cuda-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-tensorflow-rocm-py312-rhel9 Red Hat OpenShift AI (RHOAI) Under investigation rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9 Red Hat OpenShift Container Platform 4 Not affected python-mistune Red Hat Satellite 6 Under investigation satellite/iop-advisor-engine-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-59930 https://nvd.nist.gov/vuln/detail/CVE-2026-59930 https://github.com/lepture/mistune/commit/c4093c4742ed0d10d9332fb8edb455869b7b581b https://github.com/lepture/mistune/releases/tag/v3.3.0 https://github.com/lepture/mistune/security/advisories/GHSA-2hm2-hc3v-44h9