SSH vulnerabilities

A vulnerability in the SSH server of TP-Link TL-WR820N v2.80 allows the use of a weak cryptographic algorithm, enabling an adjacent attacker to intercept and decrypt SSH traffic. Exploitation may expose sensitive information and compromise confidentiality.

SSH servers parsing GSSAPI authentication requests do not validate the number of mechanisms specified in the request, allowing an attacker to cause unbounded memory consumption.

A vulnerability in the SSH restricted shell interface of the network management services allows improper access control for authenticated read-only users. If successfully exploited, this vulnerability could allow an attacker with read-only privileges to gain administrator access on the affected system.

SSH clients receiving SSH_AGENT_SUCCESS when expecting a typed response will panic and cause early termination of the client process.

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

ssh in OpenSSH before 10.1 allows control characters in usernames that originate from certain possibly untrusted sources, potentially leading to code execution when a ProxyCommand is used. The untrusted sources are the command line and %-sequence expansion of a configuration file. (A configuration file that provides a complete literal username is not categorized as an untrusted source.)

SSH Tectia Server before 6.6.6 sometimes allows attackers to read and alter a user's session traffic.

A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.

Teleport provides connectivity, authentication, access controls and audit for infrastructure. Community Edition versions before and including 17.5.1 are vulnerable to remote authentication bypass. At time of posting, there is no available open-source patch.

An OpenSSH daemon listens on TCP port 22. There is a hard-coded entry in the "/etc/shadow" file in the firmware image for the "root" user. However, in the default SSH configuration the "PermitRootLogin" is disabled, preventing the root user from logging in via SSH. This configuration can be bypassed/changed by an attacker through multiple paths though.

Erlang/OTP is a set of libraries for the Erlang programming language. Prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20, a SSH server may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access to affected systems and execute arbitrary commands without valid credentials. This issue is patched in versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20. A temporary workaround involves disabling the SSH server or to prevent access via firewall rules.

In Ubuntu, gnome-control-center did not properly reflect SSH remote login status when the system was configured to use systemd socket activation for openssh-server. This could unknowingly leave the local machine exposed to remote SSH access contrary to expectation of the user.

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

Improper input validation in OpenSSH for Windows allows an authorized attacker to elevate privileges locally.

VyOS 1.3 through 1.5 (fixed in 1.4.2) or any Debian-based system using dropbear in combination with live-build has the same Dropbear private host keys across different installations. Thus, an attacker can conduct active man-in-the-middle attacks against SSH connections if Dropbear is enabled as the SSH daemon. I n VyOS, this is not the default configuration for the system SSH daemon, but is for the console service. To mitigate this, one can run "rm -f /etc/dropbear/*key*" and/or "rm -f /etc/dropbear-initramfs/*key*" and then dropbearkey -t rsa -s 4096 -f /etc/dropbear_rsa_host_key and reload the service or reboot the system before using Dropbear as the SSH daemon (this clears out all keys mistakenly built into the release image) or update to the latest version of VyOS 1.4 or 1.5. Note that this vulnerability is not unique to VyOS and may appear in any Debian-based Linux distribution that uses Dropbear in combination with live-build, which has a safeguard against this behavior in OpenSSH but no equivalent one for Dropbear.

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.

SSH servers which implement file transfer protocols are vulnerable to a denial of service attack from clients which complete the key exchange slowly, or not at all, causing pending content to be read into memory, but never transmitted.

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.

SSH Communication Security PrivX versions between 18.0-36.0 implement insufficient validation on public key signatures when using native SSH connections via a proxy port. This allows an existing PrivX "account A" to impersonate another existing PrivX "account B" and gain access to SSH target hosts to which the "account B" has access.

Applications and libraries which misuse connection.serverAuthenticate (via callback field ServerConfig.PublicKeyCallback) may be susceptible to an authorization bypass. The documentation for ServerConfig.PublicKeyCallback says that "A call to this function does not guarantee that the key offered is in fact used to authenticate." Specifically, the SSH protocol allows clients to inquire about whether a public key is acceptable before proving control of the corresponding private key. PublicKeyCallback may be called with multiple keys, and the order in which the keys were provided cannot be used to infer which key the client successfully authenticated with, if any. Some applications, which store the key(s) passed to PublicKeyCallback (or derived information) and make security relevant determinations based on it once the connection is established, may make incorrect assumptions. For example, an attacker may send public keys A and B, and then authenticate with A. PublicKeyCallback would be called only twice, first with A and then with B. A vulnerable application may then make authorization decisions based on key B for which the attacker does not actually control the private key. Since this API is widely misused, as a partial mitigation golang.org/x/cry...@v0.31.0 enforces the property that, when successfully authenticating via public key, the last key passed to ServerConfig.PublicKeyCallback will be the key used to authenticate the connection. PublicKeyCallback will now be called multiple times with the same key, if necessary. Note that the client may still not control the last key passed to PublicKeyCallback if the connection is then authenticated with a different method, such as PasswordCallback, KeyboardInteractiveCallback, or NoClientAuth. Users should be using the Extensions field of the Permissions return value from the various authentication callbacks to record data associated with the authentication attempt instead of referencing external state. Once the connection is established the state corresponding to the successful authentication attempt can be retrieved via the ServerConn.Permissions field. Note that some third-party libraries misuse the Permissions type by sharing it across authentication attempts; users of third-party libraries should refer to the relevant projects for guidance.

A vulnerability in the SSH subsystem of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to execute operating system commands as root. This vulnerability is due to insufficient validation of user input. An attacker could exploit this vulnerability by submitting crafted input when executing remote CLI commands over SSH. A successful exploit could allow the attacker to execute commands on the underlying operating system with root-level privileges. An attacker with limited user privileges could use this vulnerability to gain complete control over the system.

SSH authenticated user when access the PAM server can execute an OS command to gain the full system access using bash. This issue affects Privileged Access Manager before 3.7.0.1.

A signal handler in sshd(8) may call a logging function that is not async-signal-safe. The signal handler is invoked when a client does not authenticate within the LoginGraceTime seconds (120 by default). This signal handler executes in the context of the sshd(8)'s privileged code, which is not sandboxed and runs with full root privileges. This issue is another instance of the problem in CVE-2024-6387 addressed by FreeBSD-SA-24:04.openssh. The faulty code in this case is from the integration of blacklistd in OpenSSH in FreeBSD. As a result of calling functions that are not async-signal-safe in the privileged sshd(8) context, a race condition exists that a determined attacker may be able to exploit to allow an unauthenticated remote code execution as root.

A Cross-Site Scripting vulnerability in Roundcube through 1.5.7 and 1.6.x through 1.6.7 allows a remote attacker to steal and send emails of a victim via a crafted e-mail message that abuses a Desanitization issue in message_body() in program/actions/mail/show.php.

A race condition vulnerability was discovered in how signals are handled by OpenSSH's server (sshd). If a remote attacker does not authenticate within a set time period, then sshd's SIGALRM handler is called asynchronously. However, this signal handler calls various functions that are not async-signal-safe, for example, syslog(). As a consequence of a successful attack, in the worst case scenario, an attacker may be able to perform a remote code execution (RCE) as an unprivileged user running the sshd server.

OpenSSH 9.5 through 9.7 before 9.8 sometimes allows timing attacks against echo-off password entry (e.g., for su and Sudo) because of an ObscureKeystrokeTiming logic error. Similarly, other timing attacks against keystroke entry could occur.

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.

Improper Authentication vulnerability in Progress MOVEit Transfer (SFTP module) can lead to Authentication Bypass.This issue affects MOVEit Transfer: from 2023.0.0 before 2023.0.11, from 2023.1.0 before 2023.1.6, from 2024.0.0 before 2024.0.2.

sshproxy is used on a gateway to transparently proxy a user SSH connection on the gateway to an internal host via SSH. Prior to version 1.6.3, any user authorized to connect to a ssh server using `sshproxy` can inject options to the `ssh` command executed by `sshproxy`. All versions of `sshproxy` are impacted. The problem is patched starting in version 1.6.3. The only workaround is to use the `force_command` option in `sshproxy.yaml`, but it's rarely relevant.

python-jose through 3.3.0 has algorithm confusion with OpenSSH ECDSA keys and other key formats. This is similar to CVE-2022-29217.

Malicious code was discovered in the upstream tarballs of xz, starting with version 5.6.0. Through a series of complex obfuscations, the liblzma build process extracts a prebuilt object file from a disguised test file existing in the source code, which is then used to modify specific functions in the liblzma code. This results in a modified liblzma library that can be used by any software linked against this library, intercepting and modifying the data interaction with this library.

The vantage6 technology enables to manage and deploy privacy enhancing technologies like Federated Learning (FL) and Multi-Party Computation (MPC). Nodes and servers get a ssh config by default that permits root login with password authentication. In a proper deployment, the SSH service is not exposed so there is no risk, but not all deployments are ideal. The default should therefore be less permissive. The vulnerability can be mitigated by removing the ssh part from the docker file and rebuilding the docker image. Version 4.2.0 patches the vulnerability.

OpenSSH through 10.0, when common types of DRAM are used, might allow row hammer attacks (for authentication bypass) because the integer value of authenticated in mm_answer_authpassword does not resist flips of a single bit. NOTE: this is applicable to a certain threat model of attacker-victim co-location in which the attacker has user privileges. NOTE: this is disputed by the Supplier, who states "we do not consider it to be the application's responsibility to defend against platform architectural weaknesses."

In ssh in OpenSSH before 9.6, OS command injection might occur if a user name or host name has shell metacharacters, and this name is referenced by an expansion token in certain situations. For example, an untrusted Git repository can have a submodule with shell metacharacters in a user name or host name.

In ssh-agent in OpenSSH before 9.6, certain destination constraints can be incompletely applied. When destination constraints are specified during addition of PKCS#11-hosted private keys, these constraints are only applied to the first key, even if a PKCS#11 token returns multiple keys.

The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the extension negotiation message), and a client and server may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in chacha20-poly1305@openssh.com and (if CBC is used) the -etm@openssh.com MAC algorithms. This also affects Maverick Synergy Java SSH API before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, PuTTY before 0.80, AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0, Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15, SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3, Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh crate before 0.40.2 for Rust.

JumpServer is an open source bastion host. When users enable MFA and use a public key for authentication, the Koko SSH server does not verify the corresponding SSH private key. An attacker could exploit a vulnerability by utilizing a disclosed public key to attempt brute-force authentication against the SSH service This issue has been patched in versions 3.6.5 and 3.5.6. Users are advised to upgrade. There are no known workarounds for this issue.

A vulnerability has been identified in MXsecurity versions prior to v1.0.1. The vulnerability may put the confidentiality and integrity of SSH communications at risk on the affected device. This vulnerability is attributed to a hard-coded SSH host key, which might facilitate man-in-the-middle attacks and enable the decryption of SSH traffic.

Aria Operations for Networks contains an Authentication Bypass vulnerability due to a lack of unique cryptographic key generation. A malicious actor with network access to Aria Operations for Networks could bypass SSH authentication to gain access to the Aria Operations for Networks CLI.

The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if an agent is forwarded to an attacker-controlled system. (Code in /usr/lib is not necessarily safe for loading into ssh-agent.) NOTE: this issue exists because of an incomplete fix for CVE-2016-10009.

The cryptography package before 41.0.2 for Python mishandles SSH certificates that have critical options.

An improper authentication vulnerability was identified in GitHub Enterprise Server that allowed an unauthorized actor to modify other users' secret gists by authenticating through an SSH certificate authority. To do so, a user had to know the secret gist's URL. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.9 and was fixed in versions 3.4.18, 3.5.15, 3.6.11, 3.7.8, and 3.8.1. This vulnerability was reported via the GitHub Bug Bounty program.

A security vulnerability has been identified in all supported versions of OpenSSL related to the verification of X.509 certificate chains that include policy constraints. Attackers may be able to exploit this vulnerability by creating a malicious certificate chain that triggers exponential use of computational resources, leading to a denial-of-service (DoS) attack on affected systems. Policy processing is disabled by default but can be enabled by passing the `-policy' argument to the command line utilities or by calling the `X509_VERIFY_PARAM_set1_policies()' function.

ssh-add in OpenSSH before 9.3 adds smartcard keys to ssh-agent without the intended per-hop destination constraints. The earliest affected version is 8.9.

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

Class org.apache.sshd.server.keyprovider.SimpleGeneratorHostKeyProvider in Apache MINA SSHD <= 2.9.1 uses Java deserialization to load a serialized java.security.PrivateKey. The class is one of several implementations that an implementor using Apache MINA SSHD can choose for loading the host keys of an SSH server.

A key management error vulnerability [CWE-320] affecting the RSA SSH host key in FortiOS 7.2.0 and below, 7.0.6 and below, 6.4.9 and below may allow an unauthenticated attacker to perform a man in the middle attack.

An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.

A vulnerability in the SSH implementation of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload. This vulnerability is due to improper handling of resources during an exceptional situation. An attacker could exploit this vulnerability by continuously connecting to an affected device and sending specific SSH requests. A successful exploit could allow the attacker to cause the affected device to reload.

Honeywell ControlEdge through R151.1 uses Hard-coded Credentials. According to FSCT-2022-0056, there is a Honeywell ControlEdge hardcoded credentials issue. The affected components are characterized as: SSH. The potential impact is: Remote code execution, manipulate configuration, denial of service. The Honeywell ControlEdge PLC and RTU product line exposes an SSH service on port 22/TCP. Login as root to this service is permitted and credentials for the root user are hardcoded without automatically changing them upon first commissioning. The credentials for the SSH service are hardcoded in the firmware. The credentials grant an attacker access to a root shell on the PLC/RTU, allowing for remote code execution, configuration manipulation and denial of service.