libssh 0.12.0

[chcg]

ChangeLog for libssh 0.12.0:
Security:

[CVE-2025-14821](http://www.libssh.org/security/advisories/CVE-2025-14821.txt): libssh loads configuration files from the C:\etc directory
on Windows
[CVE-2026-0964](http://www.libssh.org/security/advisories/CVE-2026-0964.txt): SCP Protocol Path Traversal in ssh_scp_pull_request()
[CVE-2026-0965](http://www.libssh.org/security/advisories/CVE-2026-0965.txt): Possible Denial of Service when parsing unexpected
configuration files
[CVE-2026-0966](http://www.libssh.org/security/advisories/CVE-2026-0966.txt): Buffer underflow in ssh_get_hexa() on invalid input
[CVE-2026-0967](http://www.libssh.org/security/advisories/CVE-2026-0967.txt): Specially crafted patterns could cause DoS
[CVE-2026-0968](http://www.libssh.org/security/advisories/CVE-2026-0968.txt): OOB Read in sftp_parse_longname()
[libssh-2026-sftp-extensions](http://www.libssh.org/security/advisories/libssh-2026-sftp-extensions.txt): Read buffer overrun when handling SFTP
extensions

Deprecations and removals:

Bumped minimal RSA key size to 1024 bits

New functionality:

Add support for hybrid key exchange mechanisms using Quantum Resistant cryptography for all backends. These are now preferred:
    sntrup761x25519-sha512, sntrup761x25519-sha512@openssh.com
    mlkem768nistp256-sha256
    mlkem768x25519-sha256
    mlkem1024nistp384-sha384 (only OpenSSL 3.5+ and libgcrypt)
New cmake option WITH_HERMETIC_USR
Added support for Ed25519 keys through PKCS#11
Support for host-bound public key authentication
(publickey-hostbound-v00@openssh.com)
Use curve25519 implementation from mbedTLS and libgcrypt
New functions for signing arbitrary data (commits) with SSH keys
    sshsig_sign()
    sshsig_verify()
Support for FIDO/U2F keys (internal implementation using libfido2)
    Compatible with OpenSSH: should work out of the box
    Extensible with callbacks
Add support for GSSAPI Key Exchange (RFC 4462, RFC 8732)
Add support for new configuratation options (client and server):
    RequiredRsaSize
    AddressFamily (client)
    GSSAPIKeyExchange
    GSSAPIKexAlgorithms
New option to get list of configured identities (SSH_OPTIONS_NEXT_IDENTITY)
More OpenSSH compatible percent expansion characters
Add new server auth_kbdint_function() callback
New PKI Context structure for key operations
Stability and compatibility improvements of ProxyJump

SFTP

Prevent failures when SFTP status message does not contain error message
Fix possible timeouts while waiting for SFTP messages
Support for users-groups-by-id@openssh.com extension in client
Support for SSH_FXF_TRUNC in server