{"id":"CVE-2026-115353","kind":"vulnerability","aliases":["CVE-2026-115353"],"related":[],"title":"Mistune: RST include directive reads arbitrary files via path traversal","description":"Mistune before 3.3.0 contains a path traversal vulnerability in the RST include directive that allows attackers to read arbitrary files by supplying relative or absolute paths. Attackers can submit markdown containing include directives referencing ../ sequences or absolute paths to embed sensitive files like credentials or environment data in rendered HTML.","summary":"Mistune before 3.3.0 lets an attacker supply relative or absolute paths in an RST include directive. The rendered HTML then embeds sensitive local files such as credentials or environment data.","severity":"critical","cvss":9.2,"epss":0.00387,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mistune","package","python","web-apps"],"not_affected_if":["no-untrusted-rst-input","version-3.3.0-or-later"],"how_to_check":"Check the installed mistune version with pip show mistune or pip freeze; anything below 3.3.0 is exposed. Search your code for mistune usage that renders untrusted RST input with include directives enabled.","fix":"Upgrade mistune to 3.3.0 or later.","status":"open","published_at":"2026-10-22T19:17:41+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","triaged_at":"2026-10-23T22:32:12+00:00","updated_at":"2026-10-24T07:15:51+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-23T22:32:12Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade mistune to 3.3.0 or later.\nUnknown whether a configuration workaround exists before upgrading.","reach":"internet","title":"Mistune: RST include directive reads arbitrary files via path traversal","impact":"high","summary":"Mistune before 3.3.0 lets an attacker supply relative or absolute paths in an RST include directive. The rendered HTML then embeds sensitive local files such as credentials or environment data.","category":"package","who_cares":["python","mistune","web-apps"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker reads server files such as credentials and environment secrets.","analyst_note":"Confirm from the NVD entry or the mistune release notes whether the include directive is on by default and whether the RST renderer is used by default; the sources do not say.","how_to_check":"Check the installed mistune version with pip show mistune or pip freeze; anything below 3.3.0 is exposed. Search your code for mistune usage that renders untrusted RST input with include directives enabled.","needs_analyst":true,"not_affected_if":["version-3.3.0-or-later","no-untrusted-rst-input"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000514,"input_tokens":2936,"output_tokens":441,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-115353':13A,16A '-2026':12A,15A '3.3.0':25B,55C 'absolut':32B,77C,89C 'allow':67C 'app':22B 'arbitrari':6A,71C 'attack':28B,68C,79C 'contain':56C,83C 'credenti':49B,96C 'cve':11A,14A 'data':52B,99C 'direct':4A,38B,65C,85C 'emb':43B,92C 'environ':51B,98C 'file':7A,46B,72C,94C 'html':41B,102C 'includ':3A,37B,64C,84C 'let':26B 'like':95C 'local':45B 'markdown':82C 'mistun':1A,17B,23B,53C 'packag':18B 'path':9A,33B,58C,78C,90C 'python':19B 'read':5A,70C 'referenc':86C 'relat':30B,75C 'render':40B,101C 'rst':2A,36B,63C 'sensit':44B,93C 'sequenc':87C 'submit':81C 'suppli':29B,74C 'travers':10A,59C 'via':8A 'vulner':60C 'web':21B 'web-app':20B","nicknames":[],"mitigations":[],"who_affected":null,"tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T19:17:41+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-115353","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-115353","severity":null,"published_at":"2026-10-22T19:17:41+00:00","modified_at":"2026-10-22T19:17:41+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-115353","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-115353","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T07:15:51+00:00","fetched_at":"2026-10-25T12:38:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}