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Bug #78661 ssh2_auth_pubkey_file(): Authentication failed using public key: Callback retur
Submitted: 2019-10-11 08:47 UTC Modified: 2019-10-11 09:40 UTC
Avg. Score:4.5 ± 1.0
Reproduced:27 of 30 (90.0%)
Same Version:11 (40.7%)
Same OS:14 (51.9%)
From: mistermadness at ya dot ru Assigned:
Status: Open Package: ssh2 (PECL)
PHP Version: 7.3Git-2019-10-11 (snap) OS: Debian 10
Private report: No CVE-ID: None
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 [2019-10-11 08:47 UTC] mistermadness at ya dot ru
PHP 7.3.9-1~deb10u1 (cli) (built: Sep 18 2019 10:33:23) ( NTS )

I have two virtual machines one Debian 9.3 and I connect successfully, another machine is Debian 10.1 and I recieve message ssh2_auth_pubkey_file(): Authentication failed for subscr using public key: Callback returned error.

Difference in libSSH version Debian 9.3 - libssh2/1.7.0, Debian 10 - SSH-2.0-libssh2_1.8.0

It looks like some problem with key auth.

Test script:
$this->connection = ssh2_connect($host, $port, array('hostkey'=>'ssh-rsa'));
if (ssh2_auth_pubkey_file($this->connection, $username, $rsapath, $rsapubpath)) {
  //echo "Public Key Authentication Successful\n";
} else {
  die('Public Key Authentication Failed');

Expected result:
Connect and recieve Public Key Authentication Successful

Actual result:
Warning: ssh2_auth_pubkey_file(): Authentication failed for subscr using public key: Callback returned error in /usr/local/nginx/html/cms/admin/classes/sshCron.php on line 18
Public Key Authentication Failed


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 [2019-10-11 09:40 UTC]
-Package: *Encryption and hash functions +Package: ssh2
 [2019-11-21 08:55 UTC] lukas dot zierer at abf dot ch
I have exactly the same issue with PHP 7.3.11-1~deb10u1 on Debian 10. The same script works with identical permissions on my .ssh directory and containing files on Debian 9.6 with PHP 7.1.26.
 [2020-08-07 11:47 UTC] andras dot kovacs at videosqr dot com
I have exactly the same problem. sshd debug as follows:

debug1: /home/myuser/.ssh/authorized_keys:1: matching key found: RSA SHA256:hzJgakOeZOqlCLD8Vo57PimTrqXtrgdCwpodT/vZvRw
debug1: /home/myuser/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
Accepted key RSA SHA256:hzJgakOeZOqlCLD8Vo57PimTrqXtrgdCwpodT/vZvRw found at /home/myuser/.ssh/authorized_keys:1
debug1: restore_uid: 0/0
Postponed publickey for myuser from port 43968 ssh2 [preauth]
Received disconnect from port 43968:11: PECL/ssh2 ( [preauth]
 [2020-09-13 20:05 UTC] pierre dot h dot du40 at outlook dot fr
Me too with php 7.3.22 and debian 10.

PHP error is "ssh2_auth_pubkey_file(): Authentication failed for datahosting using public key: Callback returned error" 

My solution is therefore to use a password authentication, but I would like another solution to continue using the key system
 [2021-01-05 13:10 UTC] l dot fuerderer at gmail dot com
I came across this bug report because it seemed as if I had the exact same issue. (Debian 10, PHP 7.3)

But it was just a permission problem of the private key file. Note, that you get the same error message if PHP can't read the private key. Be sure to check your permissions carefully.
 [2021-10-22 09:41 UTC] liyang1025 at gmail dot com
The libssh2 need pem format private key, please check the source code in
 [2022-04-27 13:48 UTC] pierre dot h dot du40 at outlook dot fr
Reply to liyang1025 at gmail dot com:
No doest work with PEM key
 [2023-05-03 12:49 UTC] amerkulow at yandex dot ru
The issue still exists from 2019 year, so is there any solution?
 [2023-05-07 19:32 UTC] jambu dot atchison at gmail dot com
PHP Version 8.1.2-1ubuntu2.11

1) I've checked the key file permissions and they are all correctly 0600 and readable by the PHP process. I tested with file_get_contents and am able to output both private and public key file contents from the PHP script.
2) I tested connecting to the remote server using the key file with the ssh command line from the PHP server and it works. `ssh -i KEYFILE USER@HOST`

PHP Warning:  ssh2_auth_pubkey_file(): Authentication failed for USER using public key: Username/PublicKey combination invalid in PHPFILE

ssh2_auth_pubkey_file() returns false
 [2023-05-07 19:38 UTC] jambu dot atchison at gmail dot com
Reply to jambu dot atchison at gmail dot com:

I forgot to mention, this only started occurring after I upgraded the system OS release and PHP version.

It did not happen in the previously installed version:

PHP Version 7.2.24-0ubuntu0.18.04.17
 [2023-06-14 07:18 UTC] alltravelingnews at gmail dot com
All Travelling News are sharing latest news about Travel, destination, hotel, resturants, beaches, trip, best places etc. More info to visit: (
 [2023-12-07 01:50 UTC] ikechianya1 at gmail dot com
I solved this issue by authorizing my public key in cPanel.

Go to cPanel->SSH Access->Go to your Public key(not .pub key)->Manage

and follow the process to authorize.
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