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CVE-2026-115353

Mistune before 3.3.0 Path Traversal via include Directive

9.2 Critical

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.39%Unchanged since Oct 23, 2026
90%50%10%1%

What each source reports

CVE List Score used9.2

Mistune before 3.3.0 Path Traversal via include Directive

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
CVE-2026-115353
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-22
Updated
2026-11-04
EUVDEUVD-2026-1084229.2

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
EUVD-2026-108422
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
Updated
2026-11-04
GitHub AdvisoriesGHSA-pfvv-4pq6-mx749.2

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that...

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
GHSA-pfvv-4pq6-mx74
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-22
Updated
2026-11-02
NVD9.2

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
CVE-2026-115353
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-22
Updated
2026-11-04
OSV9.2

Mistune before 3.3.0 Path Traversal via include Directive

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
CVE-2026-115353
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
Weakness
CWE-22
Updated
2026-11-05
OSVDEBIAN-CVE-2026-1153539.2

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
DEBIAN-CVE-2026-115353
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-05
Show 5 moreShow less
OSVOESA-2026-47918.6

python-mistune security update

The python-mistune package is a fast yet powerful Python Markdown parser with renderers and plugins, compatible with sane CommonMark rules.

Security Fix(es):

Mistune before 3.3.0 contains a cross-site scripting vulnerability in the Include directive that emits included .html, .xhtml, or .htm file content as raw block_html tokens. Attackers who can plant an HTML file readable by the renderer can reference it via an include directive, combined with path traversal, to execute stored scripts when escape=False is set.(CVE-2026-115350)

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.(CVE-2026-115353)

Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to read local files by supplying relative or absolute include paths. Attackers who submit Markdown rendered via Markdown.read() can disclose files such as /etc/passwd and inject unescaped HTML or script content into rendered output.(CVE-2026-115354)

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.(CVE-2026-115355)

Record
OESA-2026-4791
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-11
OSVOESA-2026-47938.6

python-mistune security update

The python-mistune package is a fast yet powerful Python Markdown parser with renderers and plugins, compatible with sane CommonMark rules.

Security Fix(es):

Mistune before 3.3.0 contains a cross-site scripting vulnerability in the Include directive that emits included .html, .xhtml, or .htm file content as raw block_html tokens. Attackers who can plant an HTML file readable by the renderer can reference it via an include directive, combined with path traversal, to execute stored scripts when escape=False is set.(CVE-2026-115350)

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.(CVE-2026-115353)

Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to read local files by supplying relative or absolute include paths. Attackers who submit Markdown rendered via Markdown.read() can disclose files such as /etc/passwd and inject unescaped HTML or script content into rendered output.(CVE-2026-115354)

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.(CVE-2026-115355)

Record
OESA-2026-4793
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-11
OSVOESA-2026-47948.6

python-mistune security update

The python-mistune package is a fast yet powerful Python Markdown parser with renderers and plugins, compatible with sane CommonMark rules.

Security Fix(es):

Mistune before 3.3.0 contains a cross-site scripting vulnerability in the Include directive that emits included .html, .xhtml, or .htm file content as raw block_html tokens. Attackers who can plant an HTML file readable by the renderer can reference it via an include directive, combined with path traversal, to execute stored scripts when escape=False is set.(CVE-2026-115350)

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.(CVE-2026-115353)

Mistune before 3.3.0 contains a path traversal vulnerability in the opt-in Include directive that allows attackers to read local files by supplying relative or absolute include paths. Attackers who submit Markdown rendered via Markdown.read() can disclose files such as /etc/passwd and inject unescaped HTML or script content into rendered output.(CVE-2026-115354)

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.(CVE-2026-115355)

Record
OESA-2026-4794
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-11
OSVUBUNTU-CVE-2026-1153539.2

Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.

Record
UBUNTU-CVE-2026-115353
CVSS 4.0
9.2 CriticalCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CVSS 3.1
8.6 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:12407-1No score

python313-mistune-3.4.0-2.1 on GA media

These are all security issues fixed in the python313-mistune-3.4.0-2.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:12407-1
Updated
2026-11-04

Affected products

Affected packages

Affected packages
PackageAffectedFixed
mistune
Debian:12
All versions, plus listed versions
2.0.4-12.0.4-23.0.2-13.0.2-23.1.3-13.1.4-13.3.4-13.4.0-1
None known
mistune
Debian:13
All versions, plus listed versions
3.1.3-13.1.4-13.3.4-13.4.0-1
None known
mistune
Debian:14
All versions, plus listed versions
3.1.3-13.1.4-13.3.4-13.4.0-1
None known
python-mistune
openEuler:24.03-LTS-SP4
From an advisory covering 4 CVEs
before 2.0.4-4.oe2403sp4
2.0.4-4.oe2403sp4
python-mistune
openEuler:24.03-LTS-SP1
From an advisory covering 4 CVEs
before 2.0.4-4.oe2403sp1
2.0.4-4.oe2403sp1
python-mistune
openEuler:24.03-LTS-SP3
From an advisory covering 4 CVEs
before 2.0.4-4.oe2403sp3
2.0.4-4.oe2403sp3
mistune
Ubuntu:16.04:LTS
All versions, plus listed versions
0.6-20.7.1-1
None known
mistune
Ubuntu:18.04:LTS
All versions, plus listed versions
0.7.4-10.8-10.8.1-10.8.3-2
None known
mistune
Ubuntu:20.04:LTS
All versions, plus listed versions
0.8.4-10.8.4-2
None known
mistune
Ubuntu:22.04:LTS
All versions, plus listed versions
0.8.4-40.8.4-52.0.0-1+really0.8.4-1
None known
Show 4 moreShow less
Affected packages
PackageAffectedFixed
mistune
Ubuntu:24.04:LTS
All versions, plus listed versions
2.0.4-23.0.2-1
None known
mistune
Ubuntu:26.10
All versions, plus listed versions
3.1.4-1
None known
mistune
Ubuntu:26.04:LTS
All versions, plus listed versions
3.1.3-13.1.4-1
None known
python-mistune
openSUSE:Tumbleweed
From an advisory covering 4 CVEs
before 3.4.0-2.1
3.4.0-2.1

History

History
RecordedChangedSources
affected, aliases, referencesOSV
affected, factsEUVD, NVD, OSV
referencesCVE List
affected, aliases, facts, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-115353 is a critical vulnerability (CVSS 9.2) in Lepture Mistune, published October 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.39%, the 33rd percentile. No source names a fixed version.

References

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