Public PoC Released for Critical libssh2 CVE-2026-55200 Client-Side SSH Flaw

A public proof-of-concept is now out for CVE-2026-55200, a critical flaw in libssh2 that lets a malicious or compromised SSH server trigger memory corruption on a connecting client, with possible code execution. No credentials, no user interaction. The bug affects every release up to and includin...

Linux Distros Unpatched Vulnerability : CVE-2026-58051

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - libssh2 through 1.11.1 grows its publickey list with SSH2REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure...

SUSE-SU-2026:22284-1 Security update for libssh2_org

This update for libssh2org fixes the following issues - CVE-2026-55199: pre-Authentication DoS via SSHMSGEXTINFO Handler bsc1268530. - CVE-2026-55200: out-of-Bounds write via Unchecked packetlength in transport.c bsc1268531...

CVE-2026-55199

A vulnerability in libssh2 allows a malicious SSH server to freeze connected clients during the handshake process. By sending a malformed packet, the server triggers a loop that exhausts the client's CPU, resulting in a denial of service. Mitigation To mitigate this issue, ensure your libssh2...

SUSE CVE-2025-15661

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftpsymlink function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSHFXPNAME response...

Linux Distros Unpatched Vulnerability : CVE-2026-55199

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSHMSGEXTINFO handler in src/packet.c that...

CVE-2026-55200

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve...

CVE-2026-55200 libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve...

EUVD-2026-37784

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve...

CVE-2026-55199 libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSHMSGEXTINFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can s...

EUVD-2026-37782

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSHMSGEXTINFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can s...

CVE-2026-55199 libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSHMSGEXTINFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can s...

Amazon Linux 2023 : libssh2, libssh2-devel (ALAS2023-2026-1779)

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-1779 advisory. A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauthpassword of the file src/userauth.c. Such manipulation of the argument...

Astra Linux – Vulnerability in libssh2

In libssh2 v1.9.0 and earlier versions, the SSHMSGDISCONNECT logic in packet.c has an integer overflow in a bounds check, allowing an attacker to specify an arbitrary out-of-bounds offset for a subsequent memory read. A malicious SSH server may be able to disclose sensitive information or cause a...

Azure Linux 3.0 Security Update: CBL-Mariner Releases (CVE-2026-7598)

The version of CBL-Mariner Releases installed on the remote Azure Linux 3.0 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the CVE-2026-7598 advisory. - A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the...

SUSE CVE-2026-7598

A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauthpassword of the file src/userauth.c. Such manipulation of the argument usernamelen/passwordlen leads to integer overflow. The attack may be launched remotely. The name of the patch is...

Linux Distros Unpatched Vulnerability : CVE-2026-7598

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauthpassword of the file src/userauth.c. Such...

MiracleLinux 4 : libssh2-1.4.2-3.AXS4.1 (AXSA:2019-3922:01)

The remote MiracleLinux 4 host has a package installed that is affected by multiple vulnerabilities as referenced in the AXSA:2019-3922:01 advisory. libssh2: Integer overflow in transport read resulting in out of bounds write CVE-2019-3855 libssh2: Integer overflow in keyboard interactive handlin...

MiracleLinux 7 : libssh2-1.4.3-12.el7.3 (AXSA:2019-3945:03)

The remote MiracleLinux 7 host has a package installed that is affected by a vulnerability as referenced in the AXSA:2019-3945:03 advisory. libssh2: Out-of-bounds memory comparison with specially crafted message channel request CVE-2019-3862 Tenable has extracted the preceding description block...

MiracleLinux 7 : libssh2-1.4.3-10.el7.1 (AXSA:2016-132:01)

The remote MiracleLinux 7 host has a package installed that is affected by a vulnerability as referenced in the AXSA:2016-132:01 advisory. libssh2 is a library implementing the SSH2 protocol as defined by Internet Drafts: SECSH-TRANS22, SECSH-USERAUTH25, SECSH-CONNECTION23, SECSH-ARCH20,...