A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSHOK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

A vulnerability was found in libssh, where the authentication check of the connecting client can be bypassed in thepkiverifydatasignature function in memory allocation problems. This issue may happen if there is insufficient memory or the memory usage is limited. The problem is caused by the return value rc, which is initialized to SSHERROR and later rewritten to save the return value of the function call pkikeycheckhashcompatible. The value of the variable is not changed between this point and the cryptographic verification. Therefore any error between them calls goto error returning SSHOK.

A Double Free vulnerability exists in libssh’s key export mechanism when built against OpenSSL 3.0 or later. The flaw lies in the pkikeytoblob() function, where a memory structure (params) is deallocated during error handling but not properly nullified. If a subsequent operation encounters an error, the same structure may be freed again, leading to undefined behavior and potential process crashes. Although exploitation requires authenticated access and specific memory failure conditions, the flaw could be leveraged to destabilize applications using libssh for exporting SSH key material.

Affected versions : libssh >= 0.10.0, built with OpenSSL >= 3.0

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.