CVE-2026-115351 Mistune 3.2.1 before 3.3.0 CSS Injection via Figure Directive figwidth Option
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-115351?
CVE-2026-115351 is a medium-severity vulnerability in lepture mistune, published on 22 Oct 2026.
Official 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.
Weakness: CWE-94
Which versions are affected by CVE-2026-115351?
How do I fix CVE-2026-115351?
No fix has been published for CVE-2026-115351 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-115351 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-115351 exists.
Sources
Also known as DEBIAN-CVE-2026-115351, GHSA-2jmw-jfgq-rw98, GHSA-xmwc-wjpr-q378, UBUNTU-CVE-2026-115351.