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.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | Upgrade curl | Jul 6, 2026 | Jul 3, 2026 |
| Amazon Linux Ami 2 | — | Upgrade libcurl-develUpgrade libcurlUpgrade curlUpgrade curl-debuginfo | Oct 19, 2026 | Oct 19, 2026 |
| Amazon_linux_2023 | — | Upgrade libcurl-develUpgrade curl-debugsourceUpgrade libcurl-debuginfoUpgrade curlUpgrade libcurlUpgrade curl-debuginfoUpgrade curl-minimal-debuginfoUpgrade libcurl-minimal-debuginfoUpgrade curl-minimalUpgrade libcurl-minimal | Sep 30, 2026 | Jul 3, 2026 |
| Redhat_linux | — | Upgrade libcurl-minimal-debuginfoUpgrade libcurl-minimalUpgrade libcurl-develUpgrade curlUpgrade curl-debuginfoUpgrade libcurlUpgrade curl-debugsourceUpgrade libcurl-debuginfo | Jul 17, 2026 | Jul 3, 2026 |
| Ubuntu | — | Upgrade libcurl4-openssl-devUpgrade libcurl4-gnutls-devUpgrade libcurl4t64Upgrade curlUpgrade libcurl3t64-gnutls | Jul 12, 2026 | Jul 9, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Aug 10, 2026 | Jul 3, 2026 |
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