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Vulnerabilities

Vulnerability · CVE-2026-115355

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.

Published Oct 22, 2026 · catalog updated Oct 23, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-115355. EPSS is 0.46%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High8.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.46%
Remediation
Advisory link
Affected products
Debian:12 mistune · Debian:13 mistune · Debian:14 mistune · pypi mistune · vendor lepture mistune

The Include directive in src/mistune/directives/include.py does not validate that the resolved file path stays within the source directory, allowing path traversal via ../ sequences to read arbitrary files. Additionally, error messages and included file contents are rendered without HTML escaping, leading to XSS even when escape=True. Affected functions: Path resolution (lines 27-31) block_error() in html.py (line 140) render_html_include() (line 72) The Include plugin must be explicitly enabled via the plugins …

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 mistune2.0.4-1, 2.0.4-2, 3.0.2-1
  • Debian:13 mistune3.1.3-1, 3.1.4-1, 3.3.4-1
  • Debian:14 mistune3.1.3-1, 3.1.4-1, 3.3.4-1
  • pypi mistuneversion unspecified
  • vendor lepture mistuneversion unspecified

How to fix CVE-2026-115355

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-115355. EPSS is 0.46%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Compare what you have installed with 2.0.4-1, 2.0.4-2, 3.0.2-1, 3.1.3-1, 3.1.4-1, 3.3.4-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-22: Path Traversal. EPSS 0.46%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Trivy Vulnerability DB

    Detected

    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.

  2. Oct 23, 2026 · Trivy Vulnerability DB

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-115355

    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 c

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-115355

    30-day exploitation probability 0.46%

    first.org
  • GitLab Advisory DatabasePackage advisoryCVE-2026-115355

    The Include directive in src/mistune/directives/include.py does not validate that the resolved file path stays within the source directory, allowing path traversal via ../ sequences to read arbitrary files. Additionally, error messages and included file contents are rendered without HTML escaping, leading to XSS even when escape=True. Affected functions: Path resolution (lines 27-31) block_error()

    advisories.gitlab.com
  • Red Hat Security DataVendor advisoryCVE-2026-115355

    mistune: mistune: Arbitrary file read via path traversal in Include directive

    access.redhat.com
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-115355

    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 c

    osv.dev

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 3, 2026
  • GitLab Advisory DatabaseOct 27, 2026
  • Red Hat Security DataOct 23, 2026
  • CVE.orgOct 23, 2026
  • Trivy Vulnerability DBOct 23, 2026