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ssh in OpenSSH before 10.4 can have a use-after-free when a server changes its host key during a key re-exchange. (This outcome occurs only on the client side.)

A security regression (CVE-2006-5051) was discovered in OpenSSH's server (sshd). There is a race condition which can lead sshd to handle some signals in an unsafe manner. An unauthenticated, remote attacker may be able to trigger it by failing to authenticate within a set time period.

In OpenSSH before 10.3, a file downloaded by scp may be installed setuid or setgid, an outcome contrary to some users' expectations, if the download is performed as root with -O (legacy scp protocol) and without -p (preserve mode).

OpenSSH before 10.3 mishandles the authorized_keys principals option in uncommon scenarios involving a principals list in conjunction with a Certificate Authority that makes certain use of comma characters.

In sshd in OpenSSH before 10.4, DisableForwarding=yes was supposed to take precedence over PermitTunnel=yes, but did not.

sshd in OpenSSH before 10.4 allows remote attackers to cause a denial of service (resource consumption from excessive authentication attempts) because MaxAuthTries was mishandled for GSSAPIAuthentication.

A vulnerability was found in OpenSSH when the VerifyHostKeyDNS option is enabled. A machine-in-the-middle attack can be performed by a malicious machine impersonating a legit server. This issue occurs due to how OpenSSH mishandles error codes in specific conditions when verifying the host key. For an attack to be considered successful, the attacker needs to manage to exhaust the client's memory resource first, turning the attack complexity high.

OpenSSH before 10.3 can use unintended ECDSA algorithms. Listing of any ECDSA algorithm in PubkeyAcceptedAlgorithms or HostbasedAcceptedAlgorithms is misinterpreted to mean all ECDSA algorithms.

sshd in OpenSSH before 10.4 has an undocumented security-relevant behavior: GSSAPIStrictAcceptorCheck has no value if the server is in Windows Active Directory.

sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay.

sftp in OpenSSH before 10.4 does not properly constrain the location of downloaded files when "sftp server:/path ." is used with an attacker-controlled server.

scp in OpenSSH before 10.4 may place a file in the parent directory of an intended directory when the copy occurs between two remote destinations.

internal-sftp in sshd in OpenSSH before 10.4 recognizes only the first 9 command-line arguments, which can be important if a later command-line argument would have helped to ensure the intended security properties of an SFTP connection.

In ssh in OpenSSH before 10.5, a use-after-free for realloc data can occur if a certain pair of remote-forwarding operations are concurrent.

In sshd in OpenSSH before 10.0, the DisableForwarding directive does not adhere to the documentation stating that it disables X11 and agent forwarding.

In ssh-agent in OpenSSH before 10.5, some operations can occur remotely but were intended to occur only locally, including operations that add tokens or use keys. This is caused by misinteraction between agent locking and the session-bind@openssh.com extension.

OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.

In sshd in OpenSSH before 10.5, the restrict keyword (in authorized_keys) was supposed to be applicable to tunnel forwarding but was not.