CVE-2026-59929

Q: How do I fix CVE-2026-59929?

Upgrade mistune to 3.3.0 or later.

Q: Is CVE-2026-59929 being actively exploited?

Not that we know of. CVE-2026-59929 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.34% is the estimated probability that it will be exploited in the next 30 days. That is higher than 27% of all scored CVEs.

Q: How severe is CVE-2026-59929?

CVE-2026-59929 has a CVSS v3 base score of 6.1, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-59929 affect?

Published advisories record a fix for mistune (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

MEDIUM

6.1

CVSS v3

NVD

Description

Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, the safe_url filter in src/mistune/renderers/html.py blocks only javascript:, vbscript:, file:, and data: schemes, allowing legacy or chained schemes such as feed:, view-source:, jar:, livescript:, mocha:, ms-its:, mk:, and res: to reach rendered href and src attributes and potentially execute script in affected user agents. This issue is fixed in version 3.3.0.

CWE-79Cross-Site Scripting (XSS)CWE-184

How to fix

Remediation Available

mistuneNVD

Affected:< 3.3.0Fixed in:3.3.0CVE-2026-59929derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.34%probability of exploitation in 30 days

27thpercentile

Low risk: more likely to be exploited than 27% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2018-12998	Medium	6.1	99%	-	-
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2021-25299	Medium	6.1	98%	-	-

Common questions

How do I fix CVE-2026-59929?

Upgrade mistune to 3.3.0 or later.

Is CVE-2026-59929 being actively exploited?

Not that we know of. CVE-2026-59929 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.34% is the estimated probability that it will be exploited in the next 30 days. That is higher than 27% of all scored CVEs.

How severe is CVE-2026-59929?

CVE-2026-59929 has a CVSS v3 base score of 6.1, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-59929 affect?

Published advisories record a fix for mistune (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-59929

Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-09.