Libssh
Monthly
Shell metacharacter injection in libssh's ProxyCommand handling allows a crafted SSH username to break out of the intended command string when the %r token is expanded. Affecting libssh deployments that use ProxyCommand with %r substitution, a low-privileged local attacker who controls the username passed to the connection can cause the shell executing the ProxyCommand to expand environment variables or alter its behavior, leaking sensitive environment data. No public exploit is identified and this is not listed in CISA KEV; CVSS rates this Low (3.9), consistent with the constrained local attack surface and limited impact.
Stack-based buffer overflow in libssh's SFTP server allows a connected client to crash the server or potentially execute code by placing files with overlong names into a directory the server subsequently lists. The flaw lives in how libssh builds the SFTP 'longname' field, concatenating attacker-influenced filenames into a fixed-size stack buffer without adequate bounds checking. There is no public exploit identified at time of analysis and EPSS is very low (0.10%), but the memory-corruption nature (CWE-121) and libssh's broad deployment make it worth prioritized patching.
Out-of-bounds read in libssh versions up to 0.11.3 allows remote attackers to cause denial of service by manipulating the idx argument in the SFTP extension name handler functions. The vulnerability resides in the sftp_extensions_get_name and sftp_extensions_get_data functions, enabling unauthenticated attackers to trigger memory access violations without user interaction. Upgrading to libssh 0.11.4 or 0.12.0 resolves this issue.
NULL pointer dereference in libssh crashes SSH clients or servers during the key exchange (KEX) process when a cryptographic memory allocation fails and the resulting NULL pointer is subsequently dereferenced. Affected products span all libssh versions per CPE data, with confirmed patching by Red Hat (RHSA-2026:18683) and upstream fixes committed to the libssh repository. No public exploit identified at time of analysis; EPSS at 0.03% (8th percentile) reflects very low observed exploitation interest, consistent with the local access requirement and high attack complexity.
A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library.
A security vulnerability in A flaw (CVSS 6.5). Remediation should follow standard vulnerability management procedures.
Cryptographic key derivation failure in libssh versions prior to 0.11.2 (when built against OpenSSL older than 3.0) can cause SSH sessions to proceed with uninitialized key material, allowing remote attackers to undermine session confidentiality and integrity. The flaw stems from inverted return-value semantics between OpenSSL and libssh in ssh_kdf(), so a silent KDF failure is treated as success. No public exploit identified at time of analysis and EPSS risk is low (0.07%), but the issue is widely shipped across Red Hat, Ubuntu, Debian and SUSE distributions and has vendor patches available.
CVE-2025-5318 is an out-of-bounds read vulnerability in libssh versions before 0.11.2 caused by an incorrect comparison check in the sftp_handle function that allows authenticated remote attackers to access memory beyond the valid handle list and retrieve invalid pointers for further processing. This vulnerability enables exposure of sensitive information or denial of service, with a CVSS score of 8.1 indicating high severity. The vulnerability requires authentication and network access but has high confidentiality and availability impact.
A flaw was found in libssh. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. No vendor patch available.
A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
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. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and EPSS exploitation probability 53.6%.
A missing allocation check in sftp server processing read requests may cause a NULL dereference on low-memory conditions. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability was found in libssh, where the authentication check of the connecting client can be bypassed in the`pki_verify_data_signature` function in memory allocation problems. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A flaw has been found in libssh in versions prior to 0.9.6. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.
libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.
A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This OS Command Injection vulnerability could allow attackers to execute arbitrary operating system commands on the host.
A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
The (1) SSH_MSG_NEWKEYS and (2) SSH_MSG_KEXDH_REPLY packet handlers in package_cb.c in libssh before 0.6.5 do not properly validate state, which allows remote attackers to cause a denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Double free vulnerability in the ssh_packet_kexinit function in kex.c in libssh 0.5.x and 0.6.x before 0.6.4 allows remote attackers to cause a denial of service via a crafted kexinit packet. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity.
The RAND_bytes function in libssh before 0.6.3, when forking is enabled, does not properly reset the state of the OpenSSL pseudo-random number generator (PRNG), which causes the state to be shared. Rated low severity (CVSS 1.9).
The publickey_from_privatekey function in libssh before 0.5.4, when no algorithm is matched during negotiations, allows remote attackers to cause a denial of service (NULL pointer dereference and. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable.
Double free vulnerability in the sftp_mkdir function in sftp.c in libssh before 0.5.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple integer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (infinite loop or crash) and possibly execute arbitrary code via unspecified vectors, which. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
The (1) publickey_make_dss, (2) publickey_make_rsa, (3) signature_from_string, (4) ssh_do_sign, and (5) ssh_sign_session_id functions in keys.c in libssh before 0.5.3 free "an invalid pointer on an. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple buffer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via unspecified vectors. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in channels.c, (3) ssh_userauth_pubkey function in auth.c, (4) sftp_parse_attr_3. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable. No vendor patch available.
libssh in Alpine Linux was patched at package version 0.11.2-r0, addressing an unspecified vulnerability tracked as CVE-2025-5449. The nature of the vulnerability - its root cause, attack vector, and impact - is not disclosed in available intelligence sources. The EPSS score of 0.52% (67th percentile) indicates moderate relative ranking among CVEs but low absolute exploitation probability. No active exploitation has been confirmed, and no public exploit code has been identified at time of analysis.
Shell metacharacter injection in libssh's ProxyCommand handling allows a crafted SSH username to break out of the intended command string when the %r token is expanded. Affecting libssh deployments that use ProxyCommand with %r substitution, a low-privileged local attacker who controls the username passed to the connection can cause the shell executing the ProxyCommand to expand environment variables or alter its behavior, leaking sensitive environment data. No public exploit is identified and this is not listed in CISA KEV; CVSS rates this Low (3.9), consistent with the constrained local attack surface and limited impact.
Stack-based buffer overflow in libssh's SFTP server allows a connected client to crash the server or potentially execute code by placing files with overlong names into a directory the server subsequently lists. The flaw lives in how libssh builds the SFTP 'longname' field, concatenating attacker-influenced filenames into a fixed-size stack buffer without adequate bounds checking. There is no public exploit identified at time of analysis and EPSS is very low (0.10%), but the memory-corruption nature (CWE-121) and libssh's broad deployment make it worth prioritized patching.
Out-of-bounds read in libssh versions up to 0.11.3 allows remote attackers to cause denial of service by manipulating the idx argument in the SFTP extension name handler functions. The vulnerability resides in the sftp_extensions_get_name and sftp_extensions_get_data functions, enabling unauthenticated attackers to trigger memory access violations without user interaction. Upgrading to libssh 0.11.4 or 0.12.0 resolves this issue.
NULL pointer dereference in libssh crashes SSH clients or servers during the key exchange (KEX) process when a cryptographic memory allocation fails and the resulting NULL pointer is subsequently dereferenced. Affected products span all libssh versions per CPE data, with confirmed patching by Red Hat (RHSA-2026:18683) and upstream fixes committed to the libssh repository. No public exploit identified at time of analysis; EPSS at 0.03% (8th percentile) reflects very low observed exploitation interest, consistent with the local access requirement and high attack complexity.
A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library.
A security vulnerability in A flaw (CVSS 6.5). Remediation should follow standard vulnerability management procedures.
Cryptographic key derivation failure in libssh versions prior to 0.11.2 (when built against OpenSSL older than 3.0) can cause SSH sessions to proceed with uninitialized key material, allowing remote attackers to undermine session confidentiality and integrity. The flaw stems from inverted return-value semantics between OpenSSL and libssh in ssh_kdf(), so a silent KDF failure is treated as success. No public exploit identified at time of analysis and EPSS risk is low (0.07%), but the issue is widely shipped across Red Hat, Ubuntu, Debian and SUSE distributions and has vendor patches available.
CVE-2025-5318 is an out-of-bounds read vulnerability in libssh versions before 0.11.2 caused by an incorrect comparison check in the sftp_handle function that allows authenticated remote attackers to access memory beyond the valid handle list and retrieve invalid pointers for further processing. This vulnerability enables exposure of sensitive information or denial of service, with a CVSS score of 8.1 indicating high severity. The vulnerability requires authentication and network access but has high confidentiality and availability impact.
A flaw was found in libssh. Rated medium severity (CVSS 4.8), this vulnerability is low attack complexity. No vendor patch available.
A flaw was found in the libssh implements abstract layer for message digest (MD) operations implemented by different supported crypto backends. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
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. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and EPSS exploitation probability 53.6%.
A missing allocation check in sftp server processing read requests may cause a NULL dereference on low-memory conditions. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A vulnerability was found in libssh, where the authentication check of the connecting client can be bypassed in the`pki_verify_data_signature` function in memory allocation problems. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
A NULL pointer dereference was found In libssh during re-keying with algorithm guessing. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
A flaw has been found in libssh in versions prior to 0.9.6. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.
libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.
A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.
A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This OS Command Injection vulnerability could allow attackers to execute arbitrary operating system commands on the host.
A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. No vendor patch available.
The (1) SSH_MSG_NEWKEYS and (2) SSH_MSG_KEXDH_REPLY packet handlers in package_cb.c in libssh before 0.6.5 do not properly validate state, which allows remote attackers to cause a denial of service. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
Double free vulnerability in the ssh_packet_kexinit function in kex.c in libssh 0.5.x and 0.6.x before 0.6.4 allows remote attackers to cause a denial of service via a crafted kexinit packet. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity.
The RAND_bytes function in libssh before 0.6.3, when forking is enabled, does not properly reset the state of the OpenSSL pseudo-random number generator (PRNG), which causes the state to be shared. Rated low severity (CVSS 1.9).
The publickey_from_privatekey function in libssh before 0.5.4, when no algorithm is matched during negotiations, allows remote attackers to cause a denial of service (NULL pointer dereference and. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable.
Double free vulnerability in the sftp_mkdir function in sftp.c in libssh before 0.5.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unspecified. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple integer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (infinite loop or crash) and possibly execute arbitrary code via unspecified vectors, which. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
The (1) publickey_make_dss, (2) publickey_make_rsa, (3) signature_from_string, (4) ssh_do_sign, and (5) ssh_sign_session_id functions in keys.c in libssh before 0.5.3 free "an invalid pointer on an. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple buffer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via unspecified vectors. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Multiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in channels.c, (3) ssh_userauth_pubkey function in auth.c, (4) sftp_parse_attr_3. Rated medium severity (CVSS 6.8), this vulnerability is remotely exploitable. No vendor patch available.
libssh in Alpine Linux was patched at package version 0.11.2-r0, addressing an unspecified vulnerability tracked as CVE-2025-5449. The nature of the vulnerability - its root cause, attack vector, and impact - is not disclosed in available intelligence sources. The EPSS score of 0.52% (67th percentile) indicates moderate relative ranking among CVEs but low absolute exploitation probability. No active exploitation has been confirmed, and no public exploit code has been identified at time of analysis.