OpenSSH vulnerabilities

A vulnerability in OpenSSH before version 10.1 allows the null character ('\0') in an ssh:// URI, potentially leading to code execution when a ProxyCommand is used.

A vulnerability in OpenSSH before version 10.1 allows control characters in usernames from potentially untrusted sources, such as the command line or %-sequence expansion in configuration files. This can lead to code execution when a ProxyCommand is used.

In sshd in OpenSSH before version 10.0, the DisableForwarding directive does not adhere to documentation, failing to disable X11 and agent forwarding.

In ssh-agent in OpenSSH before 9.6, destination constraints can be incompletely applied when adding PKCS#11-hosted private keys. Constraints are only applied to the first key, even if the PKCS#11 token returns multiple keys.

A vulnerability in sshd in OpenSSH 6.2 through 8.x before 8.8, when certain non-default configurations are used, allows privilege escalation. Helper programs for AuthorizedKeysCommand and AuthorizedPrincipalsCommand may run with privileges associated with group memberships of the sshd process if the configuration specifies running the command as a different user.

ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common scenarios, such as unconstrained agent-socket access on a legacy operating system, or the forwarding of an agent to an attacker-controlled host.

The client side in OpenSSH 5.7 through 8.4 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client). NOTE: some reports state that 8.5 and 8.6 are also affected.

The scp client in OpenSSH 8.2 incorrectly sends duplicate responses to the server upon a utimes system call failure, which allows a malicious unprivileged user on the remote server to overwrite arbitrary files in the client's download directory by creating a crafted subdirectory anywhere on the remote server.

OpenSSH 7.7 through 7.9 and 8.x before 8.1, when compiled with an experimental key type, has a pre-authentication integer overflow if a client or server is configured to use a crafted XMSS key. This leads to memory corruption and local code execution because of an error in the XMSS key parsing algorithm. The XMSS implementation is considered experimental in all released OpenSSH versions, and there is no supported way to enable it when building portable OpenSSH.

An issue was discovered in OpenSSH 7.9 due to missing character encoding in the progress display. A malicious server or Man-in-The-Middle attacker can use crafted object names to manipulate client output, e.g., by using ANSI control codes to hide additional files being transferred. This affects refresh_progress_meter() in progressmeter.c.