CVE-2026-12064
UnknownSummary
A vulnerability in curl causes the tool layer to skip initialization of SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS when using a schemeless URL with `--proto-default` sftp (or scp). This results in curl connecting to an unverified SSH remote host without raising an error.
Risk Assessment
The organization is at risk of man-in-the-middle (MITM) attacks on SFTP/SCP connections, as the missing SSH host verification allows an attacker to impersonate the server and intercept data.
Recommendation
Immediately update curl to a patched version and avoid using schemeless URLs with `--proto-default` sftp/scp until the update is applied.
Original NVD description (English source)
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.