Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00221.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
lepture mistune unaffected
Version Status Constraints
3.2.1 affected < 3.3.0
3.3.0 unaffected —

No data.

No data.

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/lepture/mistune/security/advisories/GHSA-xmwc-wjpr-q378 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-115351 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-115351 cve-icon
https://www.vulncheck.com/advisories/mistune-3.2.1-before-3.3.0-css-injection-via-figure-directive-figwidth-option cve-icon cve-icon cve-icon
History

Fri, 23 Oct 2026 12:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-79
References
Metrics threat_severity

None

 threat_severity

Moderate

Fri, 23 Oct 2026 04:00:00 +0000

Type Values Removed Values Added
First Time appeared Lepture
Lepture mistune
Vendors & Products Lepture
Lepture mistune

Fri, 23 Oct 2026 00:45:00 +0000

Type Values Removed Values Added
Description Mistune from 3.2.1 before 3.3.0 contains a CSS injection vulnerability that allows attackers controlling markdown input to inject arbitrary style declarations via the unvalidated figwidth option of the figure directive. Attackers can append declarations like background:url() to the rendered figure style attribute, forcing victim browsers to send requests to attacker servers and leak attribute values.
Title Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
First Time appeared Mistune Project
Mistune Project mistune
Weaknesses CWE-94
CPEs cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*
Vendors & Products Mistune Project
Mistune Project mistune
References
Metrics cvssV3_1

{'score': 4.7, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N'}

cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-22T19:13:27.678Z

Reserved: 2026-10-22T11:20:02.626Z

Link: CVE-2026-115351

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-22T19:17:40.920

Modified: 2026-10-22T19:17:41.033

Link: CVE-2026-115351

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-10-22T19:13:27Z

Links: CVE-2026-115351 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T14:00:18Z

Weaknesses