High severity · published Oct 22, 2026
CVE-2026-115355
Mistune before 3.3.0 Path Traversal and XSS via Include Directive
New
7.5
CVSS
0.5%
EPSS
No
On KEV
Description
Mistune before 3.3.0 contains a path traversal vulnerability in the Include directive that allows attackers to read arbitrary files by supplying ../ sequences in include paths. Attackers can also inject HTML through unescaped error messages and included file contents to perform cross-site scripting even when escape=True is set.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MI
mistune · lepture
before 3.3.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115355
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115355
github.com
https://github.com/lepture/mistune/security/advisories/GHSA-h7ww-273w-6cm8
www.vulncheck.com
https://www.vulncheck.com/advisories/mistune-before-3.3.0-path-traversal-and-xss-via-include-directive
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