Libssh2
Monthly
Free of an uninitialized, attacker-influenceable pointer in libssh2 through 1.11.1 allows a malicious SSH server to corrupt memory in any connecting client that uses the publickey subsystem. The publickey list is grown via SSH2_REALLOC without zero-initializing new entries, so a server-induced parse failure that reaches the cleanup path causes libssh2_publickey_list_free to operate on an uninitialized attrs pointer. Publicly available exploit code exists (reported by VulnCheck); no public evidence of active exploitation, and it is not listed in CISA KEV.
Heap buffer overflow in the libssh2 SSH client library (all versions through 1.11.1) lets a malicious or compromised SSH server corrupt memory in any connecting client on 32-bit platforms. The publickey subsystem reads an attacker-supplied 32-bit attribute count and multiplies it by the attribute structure size without bounds checking, so the allocation integer-overflows to an undersized buffer that the parsing loop then writes past. Publicly available exploit code exists; this is a CWE-190 integer overflow with no public exploit identified in CISA KEV, so it is not confirmed actively exploited.
Out-of-bounds heap read in libssh2 through 1.11.1 enables a malicious SFTP server or man-in-the-middle attacker to leak heap memory or crash client applications by sending a crafted SSH_FXP_NAME response with an inflated link_len during READLINK or REALPATH operations. The library is embedded in many SSH/SFTP clients (curl, Git tooling, language bindings), so impact extends to anywhere libssh2 is used as a client. No public exploit identified at time of analysis, but a vendor patch (commit 2dae302) is available and the issue was reported by VulnCheck.
Remote code execution in libssh2 through version 1.11.1 stems from an unchecked packet_length field in ssh2_transport_read() that allows attackers to send oversized SSH packets and corrupt heap memory. The flaw was reported by VulnCheck and is fixed upstream in commit 97acf3df (PR #2052), which adds an upper-bound check against LIBSSH2_PACKET_MAXPAYLOAD. No public exploit has been identified at time of analysis, but the CVSS 4.0 score of 9.2 reflects pre-authentication network reach with high impact on confidentiality, integrity, and availability.
Pre-authentication denial of service in libssh2 through 1.11.1 allows a malicious SSH server to pin a connecting client's CPU at 100% for over 60 seconds by advertising an attacker-controlled SSH_MSG_EXT_INFO extension count of 0xFFFFFFFF during key exchange. The flaw is reachable before authentication completes, so any client that initiates an SSH session to a hostile or compromised server endpoint is exposed, and no public exploit identified at time of analysis though VulnCheck has published an advisory and the upstream PR diff is public.
Integer overflow in libssh2 up to version 1.11.1 allows remote unauthenticated attackers to cause memory corruption during SSH password authentication. The vulnerability exists in the userauth_password function where inadequate bounds checking on username_len and password_len parameters can trigger integer overflow when calculating buffer sizes, potentially leading to confidentiality breach, integrity compromise, and service disruption. Upstream fix available via GitHub commit 256d04b60d80bf1190e96b0ad1e91b2174d744b1. No active exploitation confirmed (not in CISA KEV), but publicly accessible patch reveals exact exploitation technique.
Free of an uninitialized, attacker-influenceable pointer in libssh2 through 1.11.1 allows a malicious SSH server to corrupt memory in any connecting client that uses the publickey subsystem. The publickey list is grown via SSH2_REALLOC without zero-initializing new entries, so a server-induced parse failure that reaches the cleanup path causes libssh2_publickey_list_free to operate on an uninitialized attrs pointer. Publicly available exploit code exists (reported by VulnCheck); no public evidence of active exploitation, and it is not listed in CISA KEV.
Heap buffer overflow in the libssh2 SSH client library (all versions through 1.11.1) lets a malicious or compromised SSH server corrupt memory in any connecting client on 32-bit platforms. The publickey subsystem reads an attacker-supplied 32-bit attribute count and multiplies it by the attribute structure size without bounds checking, so the allocation integer-overflows to an undersized buffer that the parsing loop then writes past. Publicly available exploit code exists; this is a CWE-190 integer overflow with no public exploit identified in CISA KEV, so it is not confirmed actively exploited.
Out-of-bounds heap read in libssh2 through 1.11.1 enables a malicious SFTP server or man-in-the-middle attacker to leak heap memory or crash client applications by sending a crafted SSH_FXP_NAME response with an inflated link_len during READLINK or REALPATH operations. The library is embedded in many SSH/SFTP clients (curl, Git tooling, language bindings), so impact extends to anywhere libssh2 is used as a client. No public exploit identified at time of analysis, but a vendor patch (commit 2dae302) is available and the issue was reported by VulnCheck.
Remote code execution in libssh2 through version 1.11.1 stems from an unchecked packet_length field in ssh2_transport_read() that allows attackers to send oversized SSH packets and corrupt heap memory. The flaw was reported by VulnCheck and is fixed upstream in commit 97acf3df (PR #2052), which adds an upper-bound check against LIBSSH2_PACKET_MAXPAYLOAD. No public exploit has been identified at time of analysis, but the CVSS 4.0 score of 9.2 reflects pre-authentication network reach with high impact on confidentiality, integrity, and availability.
Pre-authentication denial of service in libssh2 through 1.11.1 allows a malicious SSH server to pin a connecting client's CPU at 100% for over 60 seconds by advertising an attacker-controlled SSH_MSG_EXT_INFO extension count of 0xFFFFFFFF during key exchange. The flaw is reachable before authentication completes, so any client that initiates an SSH session to a hostile or compromised server endpoint is exposed, and no public exploit identified at time of analysis though VulnCheck has published an advisory and the upstream PR diff is public.
Integer overflow in libssh2 up to version 1.11.1 allows remote unauthenticated attackers to cause memory corruption during SSH password authentication. The vulnerability exists in the userauth_password function where inadequate bounds checking on username_len and password_len parameters can trigger integer overflow when calculating buffer sizes, potentially leading to confidentiality breach, integrity compromise, and service disruption. Upstream fix available via GitHub commit 256d04b60d80bf1190e96b0ad1e91b2174d744b1. No active exploitation confirmed (not in CISA KEV), but publicly accessible patch reveals exact exploitation technique.