---
id: "CVE-2026-116196"
kind: "vulnerability"
aliases: ["CVE-2026-116196"]
title: "Rclone: B2 backend leaks account token and SSE-C keys on redirects"
severity: "medium"
cvss: 6.0
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["backblaze-b2", "package", "rclone", "self-hosted"]
not_affected_if: ["default-config", "no-b2-backend"]
published_at: "2026-10-25T14:17:00+00:00"
first_seen_at: "2026-10-25T14:41:23+00:00"
updated_at: "2026-10-25T14:42:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116196", "first_seen_at": "2026-10-25T14:41:23+00:00"}]
---

# Rclone: B2 backend leaks account token and SSE-C keys on redirects

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.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `rclone version` and check whether it reports a version below `v1.75.2`.
- Check whether `--b2-download-url` is set in the rclone config or command line.

## Fix

- Upgrade rclone to `v1.75.2` or later.
- Rotate the B2 application key if the affected version was used with a custom download URL on an untrusted network.

## Timeline

- 2026-10-25T14:41:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116196

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_