# CVE-2026-86410: curl redirect to SFTP or SCP bypasses host verification

Source: https://junglewise.ai/threats/cve-2026-86410-a-flaw-in-the-curl-command-line-tool-s-logic-makes-it-only-set  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-86410 · Severity: info · Published 2026-10-20

curl is a command-line tool used to transfer data over networks using URLs. When a curl user follows a redirect from HTTPS to SFTP or SCP, the tool fails to apply SSH host verification settings like known hosts checks. An attacker redirecting traffic to a malicious SSH server could intercept credentials or establish a man-in-the-middle connection without the user's intended security checks.

Technologies: [Curl](https://junglewise.ai/threats/technologies/curl-curl). Vendors: [Curl](https://junglewise.ai/threats/vendors/curl).

## Quick answers

**Is CVE-2026-86410 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86410 being exploited in the wild.

**How severe is CVE-2026-86410?** Informational severity, published 20 October 2026.

**Which products and versions are affected?** Curl 7.81.0 to 8.22.0, excluding 8.14.3, 8.16.2, 8.20.2.

**Is there a fix for CVE-2026-86410?** Yes: fixed in curl 8.23.0, 8.20.2, 8.16.2, 8.14.3. Until then: Do not allow redirects to SFTP or SCP by avoiding the --location and --proto-redir +sftp options together, or restrict which protocols can be the target of redirects.</anigation>
<parameter name="timeline">[{"kind": "disclosed", "at": "2026-08-27", "note": "Issue reported to curl project"}, {"kind": "patched", "at": "2026-10-14", "note": "curl 8.23.0 released with fix"}, {"kind": "advisory", "at": "2026-10-14", "note": "Security advisory published"}] Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86410 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-86410?** Check whether you run Curl at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in curl 8.23.0, 8.20.2, 8.16.2, 8.14.3

Do not allow redirects to SFTP or SCP by avoiding the --location and --proto-redir +sftp options together, or restrict which protocols can be the target of redirects.</anigation>
<parameter name="timeline">[{"kind": "disclosed", "at": "2026-08-27", "note": "Issue reported to curl project"}, {"kind": "patched", "at": "2026-10-14", "note": "curl 8.23.0 released with fix"}, {"kind": "advisory", "at": "2026-10-14", "note": "Security advisory published"}]

## Technical details

The curl command-line tool fails to enforce SSH host verification options (--knownhosts, --hostpubsha256, --hostpubmd5) when a redirect from HTTPS to SFTP/SCP occurs, even when --location and --proto-redir +sftp are used. This is a host validation bypass (CWE-297) affecting the command-line tool only, not libcurl. The vulnerability requires user interaction with a redirect and explicit protocol redirection settings.

## Affected products

- curl curl 7.81.0 to 8.22.0, excluding 8.14.3, 8.16.2, 8.20.2

## References

- [https://curl.se/docs/CVE-2026-86410.html](https://curl.se/docs/CVE-2026-86410.html)
- [https://curl.se/docs/CVE-2026-86410.json](https://curl.se/docs/CVE-2026-86410.json)

## Related threats

- [libcurl credentials leak in CURLINFO_EFFECTIVE_URL](https://junglewise.ai/threats/cve-2026-94266-libcurl-could-accidentally-return-a-url-for-curl-easy-getinfo-s)
- [curl Negotiate authentication credential exposure on redirect](https://junglewise.ai/threats/cve-2026-94265-when-processing-an-http-redirect-to-a-url-containing-userinfo-a)
- [curl stack overflow in MIME structure cleanup](https://junglewise.ai/threats/cve-2026-92391-a-deeply-nested-multipart-mime-structure-constructed-via-the)
- [curl remote-header-name file overwrite bypass](https://junglewise.ai/threats/cve-2026-92390-when-invoked-with-remote-header-name-j-curl-fails-to-preserve-its)
- [curl infinite loop via server response omission](https://junglewise.ai/threats/cve-2026-92387-by-permanently-omitting-the-final-control-response-line-a)