{"id":"CVE-2026-116196","kind":"vulnerability","aliases":["CVE-2026-116196"],"related":[],"title":"Rclone: B2 backend leaks account token and SSE-C keys on redirects","description":"Rclone before v1.75.2 contains a credential exposure vulnerability in the b2 backend that leaks the live account Authorization token and SSE-C keys on HTTP redirects from --b2-download-url hosts. Attackers can observe a same-host HTTPS-to-HTTP downgrade redirect to capture the cleartext B2 token, or receive cross-host redirects disclosing SSE-C customer encryption keys.","summary":"Rclone before v1.75.2 sends the live Backblaze B2 Authorization token and SSE-C customer encryption keys to hosts reached through HTTP redirects from the --b2-download-url setting. An attacker who can observe or redirect that traffic can capture the cleartext B2 token or the SSE-C keys.","severity":"medium","cvss":6.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["backblaze-b2","package","rclone","self-hosted"],"not_affected_if":["default-config","no-b2-backend"],"how_to_check":"- Run `rclone version` and check whether it reports a version below `v1.75.2`.\n- Check whether `--b2-download-url` is set in the rclone config or command line.","fix":"- Upgrade rclone to `v1.75.2` or later.\n- Rotate the B2 application key if the affected version was used with a custom download URL on an untrusted network.","status":"open","published_at":"2026-10-25T14:17:00+00:00","first_seen_at":"2026-10-25T14:41:23+00:00","triaged_at":"2026-10-25T14:42:55+00:00","updated_at":"2026-10-25T14:42:55+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T14:42:55Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade rclone to `v1.75.2` or later.\n- Rotate the B2 application key if the affected version was used with a custom download URL on an untrusted network.","reach":"network","title":"Rclone: B2 backend leaks account token and SSE-C keys on redirects","impact":"high","summary":"Rclone before v1.75.2 sends the live Backblaze B2 Authorization token and SSE-C customer encryption keys to hosts reached through HTTP redirects from the --b2-download-url setting. An attacker who can observe or redirect that traffic can capture the cleartext B2 token or the SSE-C keys.","category":"package","nicknames":[],"who_cares":["rclone","backblaze-b2","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"B2 account token and SSE-C encryption keys captured in cleartext","analyst_note":"","how_to_check":"- Run `rclone version` and check whether it reports a version below `v1.75.2`.\n- Check whether `--b2-download-url` is set in the rclone config or command line.","needs_analyst":false,"not_affected_if":["default-config","no-b2-backend"],"who_is_affected":"Teams that run rclone with the Backblaze B2 backend and set a custom `--b2-download-url`, especially where traffic passes through networks an attacker can observe or where the download host can redirect. Users of the default B2 endpoints without a custom download URL are less exposed according to the description, but the sources do not confirm this.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000614,"input_tokens":3362,"output_tokens":556,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-116196':16A,19A '-2026':15A,18A 'account':5A,95C 'attack':59B,112C 'author':36B,96C 'b2':2A,22B,35B,54B,71B,89C,108C,129C 'b2-download-url':53B,107C 'backblaz':21B,34B 'backblaze-b2':20B 'backend':3A,90C 'c':10A,41B,77B,101C,140C 'captur':68B,126C 'cleartext':70B,128C 'contain':82C 'credenti':84C 'cross':134C 'cross-host':133C 'custom':42B,141C 'cve':14A,17A 'disclos':137C 'downgrad':123C 'download':55B,109C 'encrypt':43B,142C 'exposur':85C 'host':27B,46B,111C,118C,135C 'http':49B,104C,122C 'https':120C 'https-to-http':119C 'key':11A,44B,78B,102C,143C 'leak':4A,92C 'live':33B,94C 'observ':62B,114C 'packag':23B 'rclone':1A,24B,28B,79C 'reach':47B 'receiv':132C 'redirect':13A,50B,64B,105C,124C,136C 'same-host':116C 'self':26B 'self-host':25B 'send':31B 'set':57B 'sse':9A,40B,76B,100C,139C 'sse-c':8A,39B,75B,99C,138C 'token':6A,37B,72B,97C,130C 'traffic':66B 'url':56B,110C 'v1.75.2':30B,81C 'vulner':86C","nicknames":[],"mitigations":[],"who_affected":"Teams that run rclone with the Backblaze B2 backend and set a custom `--b2-download-url`, especially where traffic passes through networks an attacker can observe or where the download host can redirect. Users of the default B2 endpoints without a custom download URL are less exposed according to the description, but the sources do not confirm this.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-25T14:17:00+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/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-2026-116196","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-116196","severity":null,"published_at":"2026-10-25T14:17:00+00:00","modified_at":"2026-10-25T14:17:00+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"}