{"id":"CVE-2026-77361","kind":"vulnerability","aliases":["CVE-2026-77361","GHSA-c5xx-h28h-f682"],"related":[],"title":"obsidian-tc : Symlink read-ACL scope bypass via lexical path checks","description":"### Impact\nACL checks ran on the lexical vault-relative path while containment used the realpath. An in-vault symlink placed under an allowed glob, whose realpath resolved into a denied folder, passed the read ACL — an intra-vault read-ACL-scope bypass. It requires an out-of-band-planted symlink (no MCP tool creates one) and is not a vault-root escape.\n\n### Patches\nFixed in **1.3.1**. Upgrade to `>= 1.3.1`. ACL enforcement now derives the realpath vault-relative path and feeds a single unified predicate at every site.\n\n### Workarounds\nDo not permit untrusted symlinks inside the vault.","summary":"obsidian-tc, an MCP server for Obsidian vaults, checks its read access rules against the vault-relative path but enforces containment on the resolved real path. A symlink inside an allowed folder that points into a denied folder passes the access check.","severity":"medium","cvss":4.7,"epss":0.001129999989643693,"exploited":false,"exploited_at":null,"products":[{"name":"obsidian-tc","fixed":["1.3.1"],"affected":"< 1.3.1","ecosystem":"npm"}],"ecosystems":["npm"],"tags":["ai-tooling","cwe-59","cwe-863","mcp","npm","obsidian","obsidian-tc"],"not_affected_if":["below-1.3.1-unaffected-version","no-acl-deny-rules","no-untrusted-symlinks-in-vault"],"how_to_check":"npm ls obsidian-tc (affected below 1.3.1)\nReview the vault for symlinks placed under allowed globs that resolve into denied folders: find <vault> -type l -ls","fix":"Upgrade obsidian-tc to >= 1.3.1 (npm install obsidian-tc@^1.3.1).\nUntil then, do not allow untrusted symlinks inside the vault.","status":"open","published_at":"2026-10-13T14:17:42+00:00","first_seen_at":"2026-10-23T19:11:31+00:00","triaged_at":"2026-10-23T20:55:23+00:00","updated_at":"2026-10-23T23:44:52+00:00","category":"ai-tooling","confidence":0.8,"triage":{"at":"2026-10-23T20:55:23Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade obsidian-tc to >= 1.3.1 (npm install obsidian-tc@^1.3.1).\nUntil then, do not allow untrusted symlinks inside the vault.","reach":"local","impact":"medium","summary":"obsidian-tc, an MCP server for Obsidian vaults, checks its read access rules against the vault-relative path but enforces containment on the resolved real path. A symlink inside an allowed folder that points into a denied folder passes the access check.","category":"ai-tooling","who_cares":["obsidian","mcp","npm","obsidian-tc"],"confidence":0.8,"needs_auth":"unknown","worst_case":"Model reads content from denied vault folders via planted symlinks","analyst_note":"","how_to_check":"npm ls obsidian-tc (affected below 1.3.1)\nReview the vault for symlinks placed under allowed globs that resolve into denied folders: find <vault> -type l -ls","needs_analyst":false,"not_affected_if":["below-1.3.1-unaffected-version","no-acl-deny-rules","no-untrusted-symlinks-in-vault"],"user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000835,"input_tokens":3002,"output_tokens":1070,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':15A,23A '-59':32B '-77361':16A,24A '-863':34B '1.3.1':156C,159C 'access':53B,83B 'acl':7A,86C,121C,128C,160C 'ai':29B 'ai-tool':28B 'allow':73B,109C 'band':137C 'bypass':9A,130C 'c5xx':19A 'check':13A,50B,84B,87C 'contain':63B,97C 'creat':143C 'cve':14A,22A 'cwe':31B,33B 'deni':79B,116C 'deriv':163C 'enforc':62B,161C 'escap':152C 'everi':177C 'f682':21A 'feed':171C 'fix':154C 'folder':74B,80B,117C 'ghsa':18A 'ghsa-c5xx-h28h-f682':17A 'glob':110C 'h28h':20A 'impact':85C 'in-vault':102C 'insid':71B,185C 'intra':124C 'intra-vault':123C 'lexic':11A,91C 'mcp':35B,45B,141C 'npm':36B 'obsidian':2A,26A,37B,39B,42B,48B 'obsidian-tc':1A,25A,38B,41B 'one':144C 'out-of-band-pl':134C 'pass':81B,118C 'patch':153C 'path':12A,60B,68B,95C,169C 'permit':182C 'place':106C 'plant':138C 'point':76B 'predic':175C 'ran':88C 'read':6A,52B,120C,127C 'read-acl':5A 'read-acl-scop':126C 'real':67B 'realpath':100C,112C,165C 'relat':59B,94C,168C 'requir':132C 'resolv':66B,113C 'root':151C 'rule':54B 'scope':8A,129C 'server':46B 'singl':173C 'site':178C 'symlink':4A,70B,105C,139C,184C 'tc':3A,27A,40B,43B 'tool':30B,142C 'unifi':174C 'untrust':183C 'upgrad':157C 'use':98C 'vault':49B,58B,93C,104C,125C,150C,167C,187C 'vault-rel':57B,92C,166C 'vault-root':149C 'via':10A 'whose':111C 'workaround':179C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-13T14:17:42+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N","cvss_by":"GitHub","poc_count":0,"sources":[{"source":"ghsa","external_id":"GHSA-c5xx-h28h-f682","url":"https://github.com/advisories/GHSA-c5xx-h28h-f682","severity":"medium","published_at":"2026-10-23T17:28:19+00:00","modified_at":"2026-10-23T17:28:20+00:00","first_seen_at":"2026-10-23T19:11:31+00:00","fetched_at":"2026-10-23T19:11:31+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-77361","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77361","severity":null,"published_at":"2026-10-13T14:17:42+00:00","modified_at":"2026-10-16T22:17:55+00:00","first_seen_at":"2026-10-23T23:44:52+00:00","fetched_at":"2026-10-23T23:44:52+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"}