Description


When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.

Related CPE's


Vulnerable

References




https://hackerone.com/reports/3797526

ExploitIssue TrackingThird Party Advisory

https://hackerone.com/reports/3797526

ExploitIssue TrackingThird Party Advisory

Weaknesses


2499f714-1537-4658-8207-48ae4bb9eae9

Secondary

CWE-297


CWE-295

CVSS impact metrics


CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

7.5 · High

Information


Source identifier

2499f714-1537-4658-8207-48ae4bb9eae9

Vulnerability status

Modified

Published

2026-07-03T07:16:24.217Z

3 months ago

Last modified

2026-09-15T07:16:26.150Z

3 weeks ago