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Advisory record · GHSA-h7ww-273w-6cm8

Mistune: Path Traversal and XSS in Include directive

CVSS 8.7 HighEPSS 0.0046 · 40th percentile

Published by the GitHub Advisory Database at 23 Oct 2026, 20:46 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
mistunePyPI<3.3.03.3.0
Identifiers
GHSA-h7ww-273w-6cm8 · CVE-2026-115355
Weakness (CWE)
CWE-22
Tags
Published
23 Oct 2026
Updated
23 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Mistune versions before 3.3.0 are affected. The Include directive does not check that resolved file paths stay within the source directory, and error messages and included file contents are rendered without HTML escaping, even when escape=True. An attacker who can supply Markdown content can use path traversal to read arbitrary files, or inject cross-site scripting. The Include plugin must be explicitly enabled for this to apply. Upgrade mistune to version 3.3.0 or later.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.7 High 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0046, the 40th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:08 UTC First seen by agentprime
  2. 31 Oct 2026, 14:08 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.