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

The Hacker News

June 29, 2026 at 7:06 AM

Overview

A recently released proof-of-concept has exposed a serious vulnerability, CVE-2026-55200, in the libssh2 library, which is widely used for client-side SSH connections. This flaw allows a malicious SSH server to cause memory corruption on a client connecting to it, potentially leading to code execution without needing user credentials or interaction. The vulnerability impacts all versions of libssh2 up to 1.11.1 and has been rated with a CVSS score of 9.2, indicating its severity. Users of affected versions are at risk of exploitation, making it crucial for them to take immediate action. Given the nature of this flaw, it poses a significant threat to systems relying on libssh2 for secure connections.

Key Takeaways

Affected Systems: libssh2 versions up to and including 1.11.1
Action Required: Users should upgrade to the latest version of libssh2 that addresses this vulnerability.
Timeline: Newly disclosed

Original Article Summary

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 including 1.11.1 and carries a CVSS 4.0 score of 9.2. libssh2 is a client-side SSH library, not a server.

Impact

libssh2 versions up to and including 1.11.1

Exploitation Status

The exploitation status is currently unknown. Monitor vendor advisories and security bulletins for updates.

Timeline

Newly disclosed

Remediation

Users should upgrade to the latest version of libssh2 that addresses this vulnerability. Specific patch numbers or versions are not mentioned, but updating to the latest release is recommended.

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to CVE, Vulnerability, Critical.

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