How severe is CVE-2026-44898?

CVE-2026-44898 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-44898 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-44898?

CVE-2026-44898 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-44898?

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

Does CVE-2026-44898 have an EU (EUVD) identifier?

Yes. CVE-2026-44898 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31995.

When was CVE-2026-44898 published?

CVE-2026-44898 was published on 2026-05-26 and last updated on 2026-06-17.

CVE-2026-44898

CVE-2026-44898 is a medium-severity vulnerability in Mistune Project Mistune with a CVSS 3.x base score of 6.1. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
EPSS exploit prediction: 0% (14th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31995
Weakness: CWE-79
Affected product: Mistune Project Mistune
Published: 2026-05-26
Last modified: 2026-06-17

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="#<id>") and the text value (used as the visible link label) are inserted into <a> tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href="#..." attribute context, injecting arbitrary HTML tags including <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.

Frequently asked questions

What is CVE-2026-44898?: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.2.1, render_toc_ul() builds a <ul> table-of-contents tree from a list of (level, id, text) tuples. Both the id value (used as href="#<id>") and the text value (used as the visible link label) are inserted into <a> tags via a plain Python format string — with no HTML escaping applied to either value. When heading IDs are derived from user-supplied heading text (the standard use-case for readable slug anchors), an attacker can craft a heading whose text breaks out of the href="#..." attribute context, injecting arbitrary HTML tags including <script> blocks directly into the rendered TOC. This vulnerability is fixed in 3.2.1.
How severe is CVE-2026-44898?: CVE-2026-44898 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-44898 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-44898?: CVE-2026-44898 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-44898?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-44898 have an EU (EUVD) identifier?: Yes. CVE-2026-44898 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31995.
When was CVE-2026-44898 published?: CVE-2026-44898 was published on 2026-05-26 and last updated on 2026-06-17.

References

Affected products (1)

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

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