How severe is CVE-2026-59925?

CVE-2026-59925 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-59925 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59925?

CVE-2026-59925 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59925?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-59925 published?

CVE-2026-59925 was published on 2026-07-08 and last updated on 2026-07-09.

CVE-2026-59925

CVE-2026-59925 is a high-severity vulnerability in Mistune Project Mistune with a CVSS 3.x base score of 7.5. 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-407.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-407
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, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.

Frequently asked questions

What is CVE-2026-59925?: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, long sequences of well-formed double-asterisk or triple-asterisk emphasis pairs around a character cause quadratic work in src/mistune/inline_parser.py because the parser scans forward for matching close markers from every potential opening run, allowing denial of service in default Mistune parsing. This issue is fixed in version 3.3.0.
How severe is CVE-2026-59925?: CVE-2026-59925 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-59925 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59925?: CVE-2026-59925 affects Mistune Project Mistune. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59925?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-59925 published?: CVE-2026-59925 was published on 2026-07-08 and last updated on 2026-07-09.

References

Affected products (1)

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

More vulnerabilities in Mistune Project Mistune

CVE-2026-59928 — High (CVSS 7.5): Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a Markdown document containing many…
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