libssh vulnerabilities

Libssh: libssh: use-after-free via data callbacks on closed channels

A flaw was found in libssh. If data packets are processed after a channel is closed, channel data callbacks can be invoked after the associated data has already been freed, leading to crashes or possible use-after-free conditions.

Libssh: libssh: denial of service via sftp responses with unknown request ids

A flaw was found in libssh. A malicious SFTP server can send responses for unknown request IDs that libssh clients keep queued indefinitely, causing unbounded memory growth and client-side denial of service.

Libssh: libssh: integrity downgrade via openssl aes-gcm tag verification

A flaw was found in libssh. Incorrect AES-GCM finalization checks in builds using the OpenSSL backend can effectively remove integrity protection, allowing an in-path attacker to modify plaintext on the wire without detection.

Libssh: libssh: information disclosure via proxycommand %r username expansion

A flaw was found in libssh. A malicious username expanded through %r in ProxyCommand handling can inject shell metacharacters, exposing environment variables and causing unintended shell behavior.

Libssh: libssh: denial of service via unchecked proxycommand fork() failure

A flaw was found in libssh. When ProxyCommand is used, an unchecked fork() failure can be stored as process ID -1; during cleanup, signals may then be sent across the caller's accessible process tree, leading to local denial of service.

Libssh: libssh: denial of service via zero advertised channel packet size

A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.

Libssh: libssh: denial of service via improper configuration file handling

A flaw was found in libssh where it can attempt to open arbitrary files during configuration parsing. A local attacker can exploit this by providing a malicious configuration file or when the system is misconfigured. This vulnerability could lead to a Denial of Service (DoS) by causing the system to try and access dangerous files, such as block devices or large system files, which can disrupt normal operations.

• Update to 0.6.3-4.3ubuntu0.6+esm4

Libssh: libssh: denial of service via inefficient regular expression processing

A flaw was found in libssh. A remote attacker, by controlling client configuration files or known_hosts files, could craft specific hostnames that when processed by the `match_pattern()` function can lead to inefficient regular expression backtracking. This can cause timeouts and resource exhaustion, resulting in a Denial of Service (DoS) for the client.

• Update to 0.6.3-4.3ubuntu0.6+esm4

Libssh: libssh: denial of service due to malformed sftp message

A flaw was found in libssh in which a malicious SFTP (SSH File Transfer Protocol) server can exploit this by sending a malformed 'longname' field within an `SSH_FXP_NAME` message during a file listing operation. This missing null check can lead to reading beyond allocated memory on the heap. This can cause unexpected behavior or lead to a denial of service (DoS) due to application crashes.

• Update to 0.6.3-4.3ubuntu0.6+esm4

Libssh: improper sanitation of paths received from scp servers

A malicious SCP server can send unexpected paths that could make the client application override local files outside of working directory. This could be misused to create malicious executable or configuration files and make the user execute them under specific consequences. This is the same issue as in OpenSSH, tracked as CVE-2019-6111.

• Update to 0.6.3-4.3ubuntu0.6+esm4

Libssh: libssh: denial of service via zero-length input in ssh_get_hexa()

A flaw was found in libssh. The API function `ssh_get_hexa()` is vulnerable to a denial of service when processing zero-length input. This can be exploited remotely by an attacker during GSSAPI (Generic Security Service Application Program Interface) authentication if the server's logging verbosity is set to `SSH_LOG_PACKET (3)` or higher. Successful exploitation could lead to a self-Denial of Service of the per-connection daemon process.

• Update to 0.6.3-4.3ubuntu0.6+esm4

libssh SFTP Extension Name sftp.c sftp_extensions_get_data out-of-bounds

A weakness has been identified in libssh up to 0.11.3. The impacted element is the function sftp_extensions_get_name/sftp_extensions_get_data of the file src/sftp.c of the component SFTP Extension Name Handler. Executing a manipulation of the argument idx can lead to out-of-bounds read. The attack may be performed from remote. Upgrading to version 0.11.4 and 0.12.0 is sufficient to resolve this issue. This patch is called 855a0853ad3abd4a6cd85ce06fce6d8d4c7a0b60. You should upgrade the affected component.

• Update to 0.6.3-4.3ubuntu0.6+esm5

Libssh: write beyond bounds in binary to base64 conversion functions

There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption. This issue affects only 32-bits builds of libssh.

• Update to 0.6.3-4.3ubuntu0.6+esm2

Libssh: null pointer dereference in libssh kex session id calculation

A flaw was found in libssh, a library that implements the SSH protocol. When calculating the session ID during the key exchange (KEX) process, an allocation failure in cryptographic functions may lead to a NULL pointer dereference. This issue can cause the client or server to crash.

• Update to 0.6.3-4.3ubuntu0.6+esm3

Libssh: use of uninitialized variable in privatekey_from_file()

A vulnerability was found in libssh, where an uninitialized variable exists under certain conditions in the privatekey_from_file() function. This flaw can be triggered if the file specified by the filename doesn't exist and may lead to possible signing failures or heap corruption.

• Update to 0.6.3-4.3ubuntu0.6+esm2

Libssh: incorrect return code handling in ssh_kdf() in libssh

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.

Libssh: out-of-bounds read in sftp_handle()

A flaw was found in the libssh library in versions less than 0.11.2. An out-of-bounds read can be triggered in the sftp_handle function due to an incorrect comparison check that permits the function to access memory beyond the valid handle list and to return an invalid pointer, which is used in further processing. This vulnerability allows an authenticated remote attacker to potentially read unintended memory regions, exposing sensitive information or affect service behavior.

• Update to 0.6.3-4.3ubuntu0.6+esm2

Libssh: proxycommand/proxyjump features allow injection of malicious code through hostname

A flaw was found in libssh. By utilizing the ProxyCommand or ProxyJump feature, users can exploit unchecked hostname syntax on the client. This issue may allow an attacker to inject malicious code into the command of the features mentioned through the hostname parameter.

• Update to 0.6.3-4.3ubuntu0.6+esm1

Libssh: missing checks for return values for digests

A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. The return values from these were not properly checked, which could cause low-memory situations failures, NULL dereferences, crashes, or usage of the uninitialized memory as an input for the KDF. In this case, non-matching keys will result in decryption/integrity failures, terminating the connection.

• Update to 0.6.3-4.3ubuntu0.6+esm1

CVE-2023-1667

A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. This issue may allow an authenticated client to cause a denial of service.