When libcurl uses libssh2 with a hashed known_hosts file, an unrelated initial entry can cause host key validation to report a key mismatch as a missing key to the CURLOPT_SSH_KEYFUNCTION callback.
known_hosts
CURLOPT_SSH_KEYFUNCTION
{ "urgency": "not yet assigned" }
"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-87865.json"