Vulnerability · Published Oct 22, 2026 · Assigned by VulnCheck
CVE-2026-115354Mistune before 3.3.0 Arbitrary Local File Read via Include Directive
Medium 6.5
In plain English
A medium-severity path traversal in mistune from lepture. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.5%top 59.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | mistune | no fix listed | DEBIAN-CVE-2026-115354 |
| Debian:13 | mistune | no fix listed | DEBIAN-CVE-2026-115354 |
| Debian:14 | mistune | no fix listed | DEBIAN-CVE-2026-115354 |
| Ubuntu:22.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115354 |
| Ubuntu:24.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115354 |
| Ubuntu:26.04:LTS | mistune | no fix listed | UBUNTU-CVE-2026-115354 |
| Ubuntu:26.10 | mistune | no fix listed | UBUNTU-CVE-2026-115354 |
Affected products (as reported)
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
- GitHub Security Advisory (GHSA-jhcm-5rpf-j3wv) vendor-advisory
- VulnCheck Advisory: Mistune before 3.3.0 Arbitrary Local File Read via Include Directive third-party-advisory