Vulnerability · Published Oct 22, 2026 · Assigned by VulnCheck
CVE-2026-115350Mistune before 3.3.0 Stored XSS via Include Directive HTML Files
Medium 6.1
In plain English
A medium-severity cross-site scripting in mistune from lepture. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities).
Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.2%top 91.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | mistune | no fix listed | DEBIAN-CVE-2026-115350 |
| Debian:13 | mistune | no fix listed | DEBIAN-CVE-2026-115350 |
| Debian:14 | mistune | no fix listed | DEBIAN-CVE-2026-115350 |
| Ubuntu:22.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115350 |
| Ubuntu:24.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115350 |
| Ubuntu:26.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115350 |
| Ubuntu:26.10 | mistune | no fix listed | UBUNTU-CVE-2026-115350 |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
References
- GitHub Security Advisory (GHSA-96vr-jm8v-g22j) vendor-advisory
- VulnCheck Advisory: Mistune before 3.3.0 Stored XSS via Include Directive HTML Files third-party-advisory