In OpenBSD through 7.8, the slaacd and rad daemons have an infinite loop when they receive a crafted ICMPv6 Neighbor Discovery (ND) option (over a local network) with length zero, because of an "nd_opt_len * 8 - 2" expression with no preceding check for whether nd_opt_len is zero.
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 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).
In OpenSSH before 10.3, command execution can occur via shell metacharacters in a username within a command line. This requires a scenario where the username on the command line is untrusted, and also requires a non-default configurations of % in ssh_config.
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.
In sshd in OpenSSH before 10.0, the DisableForwarding directive does not adhere to the documentation stating that it disables X11 and agent forwarding.
A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack.
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.