How severe is CVE-2026-59930?

CVE-2026-59930 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-59930 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59930?

CVE-2026-59930 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59930?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-59930 published?

CVE-2026-59930 was published on 2026-07-08 and last updated on 2026-07-09.

CVE-2026-59930

CVE-2026-59930 is a medium-severity vulnerability in Mistune Project Mistune with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-345.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-345
Affected product: Mistune Project Mistune
Published: 2026-07-08
Last modified: 2026-07-09

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-59930?: CVE-2026-59930 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-59930 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59930?: CVE-2026-59930 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59930?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-59930 published?: CVE-2026-59930 was published on 2026-07-08 and last updated on 2026-07-09.

References

Affected products (1)

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

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