{"id":"CVE-2026-107571","kind":"vulnerability","aliases":["CVE-2026-107571"],"related":[],"title":"hMailServer installer: non-default folder lets local users run code as SYSTEM","description":"Incorrect default permissions in the Windows installer of Progressive Robot hMailServer 6.0.0 through 6.3.6 allow a local authenticated user to run code as the mail server's high-privileged accounts when the product is installed in a folder whose permissions are inherited from a writable parent, such as the root of a drive. The installer places the server's programs in the Bin folder of the program folder and gives neither the program folder nor Bin any permissions of their own, so they inherit the parent's. Under the default location, Program Files, ordinary users receive only read and execute and the configuration is not affected; but the installer accepts any path without warning, and a program folder at the root of an NTFS volume inherits write access for a broad group - Authenticated Users (Modify) on a Windows client, Users (create files and folders) on Windows Server. A local user without administrator rights can then alter or replace the service program, which runs as LocalSystem or as the service's virtual account, or the programs an administrator runs elevated from Bin during setup and maintenance, or place a library in Bin that those programs load in place of the system copy, gaining code execution with those privileges. The default Program Files installation is not affected.","summary":"hMailServer 6.0.0 through 6.3.6 installed to a folder that inherits writable permissions, such as a drive root, lets a local user without admin rights replace server programs. The attacker gains code execution with LocalSystem or the service's virtual account privileges.","severity":"high","cvss":7.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["hmailserver","mail-server","package","windows"],"not_affected_if":["default-config","program-files-install"],"how_to_check":"- Find the hMailServer install path (default is under Program Files); if it sits at a drive root or any folder inheriting write access for Authenticated Users or Users, it is exposed.\n- Check the folder ACL with `icacls \"C:\\path\\to\\hMailServer\"` and look for Authenticated Users (M) or Users (CI)(AD) write rights.\n- Confirm the installed version is in the range 6.0.0 through 6.3.6.","fix":"- Upgrade hMailServer to a version after `6.3.6` (fixed version unknown from sources).\n- Reinstall hMailServer under the default Program Files path, which the sources say is not affected.\n- Remove write permissions for Authenticated Users and Users from the install folder and its Bin subfolder.","status":"open","published_at":"2026-10-19T16:17:01+00:00","first_seen_at":"2026-10-23T21:57:18+00:00","triaged_at":"2026-10-25T03:10:15+00:00","updated_at":"2026-10-25T03:10:15+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T03:10:15Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade hMailServer to a version after `6.3.6` (fixed version unknown from sources).\n- Reinstall hMailServer under the default Program Files path, which the sources say is not affected.\n- Remove write permissions for Authenticated Users and Users from the install folder and its Bin subfolder.","reach":"local","title":"hMailServer installer: non-default folder lets local users run code as SYSTEM","impact":"high","summary":"hMailServer 6.0.0 through 6.3.6 installed to a folder that inherits writable permissions, such as a drive root, lets a local user without admin rights replace server programs. The attacker gains code execution with LocalSystem or the service's virtual account privileges.","category":"package","nicknames":[],"who_cares":["windows","hmailserver","mail-server"],"confidence":0.7,"needs_auth":"yes","worst_case":"local user runs code as LocalSystem on the mail server","analyst_note":"Confirm the fixed hMailServer version and vendor advisory; sources only give the affected range 6.0.0 through 6.3.6 and no patch.","how_to_check":"- Find the hMailServer install path (default is under Program Files); if it sits at a drive root or any folder inheriting write access for Authenticated Users or Users, it is exposed.\n- Check the folder ACL with `icacls \"C:\\path\\to\\hMailServer\"` and look for Authenticated Users (M) or Users (CI)(AD) write rights.\n- Confirm the installed version is in the range 6.0.0 through 6.3.6.","needs_analyst":true,"not_affected_if":["default-config","program-files-install"],"who_is_affected":"Windows servers running hMailServer 6.0.0 through 6.3.6 that were installed to a path inheriting writable permissions, such as the root of an NTFS drive. Installations under the default Program Files path are not affected, and the configuration is not affected in that case. Systems where only Program Files was used can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"high"},"cost_usd":0.000717,"input_tokens":3605,"output_tokens":713,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-107571':16A,19A '-2026':15A,18A '6.0.0':27B,78C '6.3.6':29B,80C 'accept':177C 'access':195C 'account':65B,97C,239C 'admin':48B 'administr':219C,244C 'affect':173C,282C 'allow':81C 'alter':223C 'attack':54B 'authent':84C,200C 'bin':130C,143C,248C,258C 'broad':198C 'client':206C 'code':11A,56B,88C,270C 'configur':170C 'copi':268C 'creat':208C 'cve':14A,17A 'default':5A,68C,157C,276C 'drive':41B,120C 'elev':246C 'execut':57B,167C,271C 'file':160C,209C,278C 'folder':6A,33B,105C,131C,135C,141C,185C,211C 'gain':55B,269C 'give':137C 'group':199C 'high':95C 'high-privileg':94C 'hmailserv':1A,20B,26B,77C 'incorrect':67C 'inherit':35B,109C,151C,193C 'instal':2A,30B,73C,102C,122C,176C,279C 'let':7A,43B 'librari':256C 'load':262C 'local':8A,45B,83C,216C 'localsystem':59B,232C 'locat':158C 'mail':22B,91C 'mail-serv':21B 'mainten':252C 'modifi':202C 'neither':138C 'non':4A 'non-default':3A 'ntfs':191C 'ordinari':161C 'packag':24B 'parent':113C,153C 'path':179C 'permiss':37B,69C,107C,145C 'place':123C,254C,264C 'privileg':66B,96C,274C 'product':100C 'program':52B,127C,134C,140C,159C,184C,228C,242C,261C,277C 'progress':75C 'read':165C 'receiv':163C 'replac':50B,225C 'right':49B,220C 'robot':76C 'root':42B,117C,188C 'run':10A,87C,230C,245C 'server':23B,51B,92C,125C,214C 'servic':62B,227C,236C 'setup':250C 'system':13A,267C 'user':9A,46B,85C,162C,201C,207C,217C 'virtual':64B,238C 'volum':192C 'warn':181C 'whose':106C 'window':25B,72C,205C,213C 'without':47B,180C,218C 'writabl':36B,112C 'write':194C","nicknames":[],"mitigations":[],"who_affected":"Windows servers running hMailServer 6.0.0 through 6.3.6 that were installed to a path inheriting writable permissions, such as the root of an NTFS drive. Installations under the default Program Files path are not affected, and the configuration is not affected in that case. Systems where only Program Files was used can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-19T16:17:01+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"cve@gitlab.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-107571","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107571","severity":null,"published_at":"2026-10-19T16:17:01+00:00","modified_at":"2026-10-20T20:17:14+00:00","first_seen_at":"2026-10-23T21:57:18+00:00","fetched_at":"2026-10-23T22:28:57+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"}