iked in OpenIKED, as used in OpenBSD through 6.7, allows authentication bypass because ca.c has the wrong logic for checking whether a public key matches.

libc in OpenBSD 6.6 allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/auth_subr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).

The client in OpenSSH before 7.2 mishandles failed cookie generation for untrusted X11 forwarding and relies on the local X11 server for access-control decisions, which allows remote X11 clients to trigger a fallback and obtain trusted X11 forwarding privileges by leveraging configuration issues on this X11 server, as demonstrated by lack of the SECURITY extension on this X11 server.

OpenSSH before 3.0.1 with Kerberos V enabled does not properly authenticate users, which could allow remote attackers to login unchallenged.

sshd in OpenSSH 3.2.2, when using YP with netgroups and under certain conditions, may allow users to successfully authenticate and log in with another user's password.

Vulnerability in OpenBSD 3.0, when using YP with netgroups in the password database, causes (1) rexec or (2) rsh to run another user's shell, or (3) atrun to change to a different user's directory, possibly due to memory allocation failures or an incorrect call to auth_approval().

Buffer overflow in OpenSSH before 2.9.9, and 3.x before 3.2.1, with Kerberos/AFS support and KerberosTgtPassing or AFSTokenPassing enabled, allows remote and local authenticated users to gain privileges.

KAME-derived implementations of IPsec on NetBSD 1.5.2, FreeBSD 4.5, and other operating systems, does not properly consult the Security Policy Database (SPD), which could cause a Security Gateway (SG) that does not use Encapsulating Security Payload (ESP) to forward forged IPv4 packets.

OpenSSH before 2.9.9, while using keypairs and multiple keys of different types in the ~/.ssh/authorized_keys2 file, may not properly handle the "from" option associated with a key, which could allow remote attackers to login from unauthorized IP addresses.

Buffer overflow in BSD line printer daemon (in.lpd or lpd) in various BSD-based operating systems allows remote attackers to execute arbitrary code via an incomplete print job followed by a request to display the printer queue.

The SSH protocols 1 and 2 (aka SSH-2) as implemented in OpenSSH and other packages have various weaknesses which can allow a remote attacker to obtain the following information via sniffing: (1) password lengths or ranges of lengths, which simplifies brute force password guessing, (2) whether RSA or DSA authentication is being used, (3) the number of authorized_keys in RSA authentication, or (4) the lengths of shell commands.

OpenSSH before 2.9.9, when running sftp using sftp-server and using restricted keypairs, allows remote authenticated users to bypass authorized_keys2 command= restrictions using sftp commands.

mopd (Maintenance Operations Protocol loader daemon) does not properly cleanse user-injected format strings, which allows remote attackers to execute arbitrary commands.

OpenSSH SSH client before 2.3.0 does not properly disable X11 or agent forwarding, which could allow a malicious SSH server to gain access to the X11 display and sniff X11 events, or gain access to the ssh-agent.

Untrusted search path vulnerability in ssh-agent.c in ssh-agent in OpenSSH before 7.4 allows remote attackers to execute arbitrary local PKCS#11 modules by leveraging control over a forwarded agent-socket.

login_radius on OpenBSD 3.2, 3.5, and possibly other versions does not verify the shared secret in a response packet from a RADIUS server, which allows remote attackers to bypass authentication by spoofing server replies.

Use-after-free vulnerability in OpenSMTPD before 5.7.2 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via vectors involving req_ca_vrfy_smtp and req_ca_vrfy_mta.

Off-by-one error in the OBJ_obj2txt function in LibreSSL before 2.3.1 allows remote attackers to cause a denial of service (program crash) or possible execute arbitrary code via a crafted X.509 certificate, which triggers a stack-based buffer overflow. Note: this vulnerability exists because of an incorrect fix for CVE-2014-3508.

Double free vulnerability in the ssl_parse_clienthello_use_srtp_ext function in d1_srtp.c in LibreSSL before 2.1.2 allows remote attackers to cause a denial of service or possibly have unspecified other impact by triggering a certain length-verification error during processing of a DTLS handshake.

Integer overflow in the xdrmem_getbytes() function, and possibly other functions, of XDR (external data representation) libraries derived from SunRPC, including libnsl, libc, glibc, and dietlibc, allows remote attackers to execute arbitrary code via certain integer values in length fields, a different vulnerability than CVE-2002-0391.

The hash_buffer function in schnorr.c in OpenSSH through 6.4, when Makefile.inc is modified to enable the J-PAKE protocol, does not initialize certain data structures, which might allow remote attackers to cause a denial of service (memory corruption) or have unspecified other impact via vectors that trigger an error condition.

Buffer overflow in mopd (Maintenance Operations Protocol loader daemon) allows remote attackers to execute arbitrary commands via a long file name.

IPFilter 3.4.16 and earlier does not include sufficient session information in its cache, which allows remote attackers to bypass access restrictions by sending fragmented packets to a restricted port after sending unfragmented packets to an unrestricted port.

ftpd in OpenBSD 4.3, FreeBSD 7.0, NetBSD 4.0, Solaris, and possibly other operating systems interprets long commands from an FTP client as multiple commands, which allows remote attackers to conduct cross-site request forgery (CSRF) attacks and execute arbitrary FTP commands via a long ftp:// URI that leverages an existing session from the FTP client implementation in a web browser.

ssh in OpenSSH before 4.7 does not properly handle when an untrusted cookie cannot be created and uses a trusted X11 cookie instead, which allows attackers to violate intended policy and gain privileges by causing an X client to be treated as trusted.

Unspecified vulnerability in the sshd Privilege Separation Monitor in OpenSSH before 4.5 causes weaker verification that authentication has been successful, which might allow attackers to bypass authentication. NOTE: as of 20061108, it is believed that this issue is only exploitable by leveraging vulnerabilities in the unprivileged process, which are not known to exist.

OpenBSD 3.3 and 3.4 does not properly parse Accept and Deny rules without netmasks on big-endian 64-bit platforms such as SPARC64, which may allow remote attackers to bypass access restrictions.

PF in certain OpenBSD versions, when stateful filtering is enabled, does not limit packets for a session to the original interface, which allows remote attackers to bypass intended packet filters via spoofed packets to other interfaces.

mod_digest_apple for Apache 1.3.31 and 1.3.32 on Mac OS X Server does not properly verify the nonce of a client response, which allows remote attackers to replay credentials.

Multiple integer overflows in (1) the xpmParseColors function in parse.c, (2) XpmCreateImageFromXpmImage, (3) CreateXImage, (4) ParsePixels, and (5) ParseAndPutPixels for libXpm before 6.8.1 may allow remote attackers to execute arbitrary code via a malformed XPM image file.

Multiple stack-based buffer overflows in (1) xpmParseColors in parse.c, (2) ParseAndPutPixels in create.c, and (3) ParsePixels in parse.c for libXpm before 6.8.1 allow remote attackers to execute arbitrary code via a malformed XPM image file.

Buffer overflow in named in BIND 4 versions 4.9.10 and earlier, and 8 versions 8.3.3 and earlier, allows remote attackers to execute arbitrary code via a certain DNS server response containing SIG resource records (RR).

"Memory bugs" in OpenSSH 3.7.1 and earlier, with unknown impact, a different set of vulnerabilities than CVE-2003-0693 and CVE-2003-0695.

Multiple "buffer management errors" in OpenSSH before 3.7.1 may allow attackers to cause a denial of service or execute arbitrary code using (1) buffer_init in buffer.c, (2) buffer_free in buffer.c, or (3) a separate function in channels.c, a different vulnerability than CVE-2003-0693.

OpenSSH 3.6.1 and earlier, when restricting host access by numeric IP addresses and with VerifyReverseMapping disabled, allows remote attackers to bypass "from=" and "user@host" address restrictions by connecting to a host from a system whose reverse DNS hostname contains the numeric IP address.

lib/libc/stdlib/random.c in OpenBSD returns 0 when seeded with 0.

The PAM conversation function in OpenSSH 3.7.1 and 3.7.1p1 interprets an array of structures as an array of pointers, which allows attackers to modify the stack and possibly gain privileges.

OpenSSH 2.9 and earlier does not initiate a Pluggable Authentication Module (PAM) session if commands are executed with no pty, which allows local users to bypass resource limits (rlimits) set in pam.d.

A "potential buffer overflow in ruleset parsing" for Sendmail 8.12.9, when using the nonstandard rulesets (1) recipient (2), final, or (3) mailer-specific envelope recipients, has unknown consequences.

A flaw exists in OpenBSD's implementation of the stack guard page that allows attackers to bypass it resulting in arbitrary code execution using setuid binaries such as /usr/bin/at. This affects OpenBSD 6.1 and possibly earlier versions.

The OpenSSH server, as used in Fedora and Red Hat Enterprise Linux 7 and when running in a Kerberos environment, allows remote authenticated users to log in as another user when they are listed in the .k5users file of that user, which might bypass intended authentication requirements that would force a local login.

In OpenBSD 6.6, local users can use the su -L option to achieve any login class (often excluding root) because there is a logic error in the main function in su/su.c.

OpenSSH 4.6 and earlier, when ChallengeResponseAuthentication is enabled, allows remote attackers to determine the existence of user accounts by attempting to authenticate via S/KEY, which displays a different response if the user account exists, a similar issue to CVE-2001-1483.

SSH protocol 2 (aka SSH-2) public key authentication in the development snapshot of OpenSSH 2.3.1, available from 2001-01-18 through 2001-02-08, does not perform a challenge-response step to ensure that the client has the proper private key, which allows remote attackers to bypass authentication as other users by supplying a public key from that user's authorized_keys file.

An issue was discovered in OpenSSH before 8.9. If a client is using public-key authentication with agent forwarding but without -oLogLevel=verbose, and an attacker has silently modified the server to support the None authentication option, then the user cannot determine whether FIDO authentication is going to confirm that the user wishes to connect to that server, or that the user wishes to allow that server to connect to a different server on the user's behalf. NOTE: the vendor's position is "this is not an authentication bypass, since nothing is being bypassed.

A flaw in the authentication mechanism in the Login Panel of router D-Link DSL-3782 (A1_WI_20170303 || SWVer="V100R001B012" FWVer="3.10.0.24" FirmVer="TT_77616E6771696F6E67") allows unauthenticated attackers to perform arbitrary modification (read, write) to passwords and configurations meanwhile an administrator is logged into the web panel.