{"id":"CVE-2026-116188","kind":"vulnerability","aliases":["CVE-2026-116188"],"related":[],"title":"rclone: integer overflow in S3 multipart upload lets attackers exhaust memory","description":"rclone serve s3 versions 1.75.0 before 1.75.2 contain an integer overflow vulnerability in multipart reorder-memory accounting that bypasses the configured buffer limit. Attackers can open two concurrent current-part PUT requests declaring huge lengths to wrap the signed int64 counter and retain out-of-order parts in memory, exhausting the host.","summary":"rclone serve s3 versions 1.75.0 before 1.75.2 miscount memory used for out-of-order multipart parts because a signed int64 counter wraps. An attacker sending two concurrent part uploads with huge declared lengths can bypass the configured buffer limit and exhaust host memory.","severity":"medium","cvss":6.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["package","rclone","s3","self-hosted"],"not_affected_if":["client-only-use","version-outside-range"],"how_to_check":"- Run `rclone version` and check whether it reports a version from `1.75.0` up to, but not including, `1.75.2`\n- Check whether `rclone serve s3` is running on the host, for example with `ps aux | grep \"rclone serve s3\"`","fix":"- Upgrade rclone to `1.75.2` or later\n- Until upgraded, stop exposing `rclone serve s3` to untrusted networks","status":"open","published_at":"2026-10-25T14:16:58+00:00","first_seen_at":"2026-10-25T14:41:23+00:00","triaged_at":"2026-10-25T14:42:40+00:00","updated_at":"2026-10-25T14:42:40+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T14:42:40Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade rclone to `1.75.2` or later\n- Until upgraded, stop exposing `rclone serve s3` to untrusted networks","reach":"network","title":"rclone: integer overflow in S3 multipart upload lets attackers exhaust memory","impact":"medium","summary":"rclone serve s3 versions 1.75.0 before 1.75.2 miscount memory used for out-of-order multipart parts because a signed int64 counter wraps. An attacker sending two concurrent part uploads with huge declared lengths can bypass the configured buffer limit and exhaust host memory.","category":"package","nicknames":[],"who_cares":["rclone","self-hosted","s3"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker exhausts host memory, causing denial of service on the server","analyst_note":"","how_to_check":"- Run `rclone version` and check whether it reports a version from `1.75.0` up to, but not including, `1.75.2`\n- Check whether `rclone serve s3` is running on the host, for example with `ps aux | grep \"rclone serve s3\"`","needs_analyst":false,"not_affected_if":["client-only-use","version-outside-range"],"who_is_affected":"Teams that run rclone's S3-compatible server (rclone serve s3) and accept multipart uploads from clients they do not fully trust. Hosts that only use rclone as a client, or that run versions outside 1.75.0 to 1.75.2, are not affected by this flaw.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000615,"input_tokens":3354,"output_tokens":559,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-116188':14A,17A '-2026':13A,16A '1.75.0':28B,72C '1.75.2':30B,74C 'account':85C 'attack':9A,48B,92C 'buffer':62B,90C 'bypass':59B,87C 'concurr':51B,96C 'configur':61B,89C 'contain':75C 'counter':45B,110C 'current':98C 'current-part':97C 'cve':12A,15A 'declar':56B,102C 'exhaust':10A,65B,120C 'host':23B,66B,122C 'huge':55B,103C 'int64':44B,109C 'integ':2A,77C 'length':57B,104C 'let':8A 'limit':63B,91C 'memori':11A,32B,67B,84C,119C 'miscount':31B 'multipart':6A,39B,81C 'open':94C 'order':38B,116C 'out-of-ord':35B,113C 'overflow':3A,78C 'packag':18B 'part':40B,52B,99C,117C 'put':100C 'rclone':1A,19B,24B,68C 'reorder':83C 'reorder-memori':82C 'request':101C 'retain':112C 's3':5A,20B,26B,70C 'self':22B 'self-host':21B 'send':49B 'serv':25B,69C 'sign':43B,108C 'two':50B,95C 'upload':7A,53B 'use':33B 'version':27B,71C 'vulner':79C 'wrap':46B,106C","nicknames":[],"mitigations":[],"who_affected":"Teams that run rclone's S3-compatible server (rclone serve s3) and accept multipart uploads from clients they do not fully trust. Hosts that only use rclone as a client, or that run versions outside 1.75.0 to 1.75.2, are not affected by this flaw.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-25T14:16:58+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/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-2026-116188","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-116188","severity":null,"published_at":"2026-10-25T14:16:58+00:00","modified_at":"2026-10-25T14:16:58+00:00","first_seen_at":"2026-10-25T14:41:23+00:00","fetched_at":"2026-10-25T14:41:23+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"}