CVE-2026-115351

Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option

State: Published
Severity: 5.3 Medium
Published: Oct 22, 2026
Updated: Oct 29, 2026
Reserved: Oct 22, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	5.3 Medium	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	VulnCheck
3.1	4.7 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N	VulnCheck

Weaknesses

CWE-94 Improper Control of Generation of Code ('Code Injection')

Affected Products

Product	Versions
mistunelepture	3.2.1 to before 3.3.0Affected 3.3.0Not affected

References

GitHub Security Advisory (GHSA-xmwc-wjpr-q378)vendor-advisory
VulnCheck Advisory: Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Optionthird-party-advisory

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