Heap Buffer Overflow in libssh2 Client Library

Executive Summary

CVE-2026-58050 is a high-severity integer overflow vulnerability in libssh2 versions up to and including 1.11.1. The vulnerability occurs in the publickey subsystem when libssh2 reads a 32-bit attribute count from a malicious SSH server's response. This attribute count is used to calculate memory allocation without proper bounds checking. On 32-bit platforms, this calculation can overflow, resulting in an undersized buffer.

Because of this overflow, an attacker-controlled SSH server can exploit the vulnerability by causing the attribute-parsing loop to write beyond the allocated memory buffer, leading to a heap buffer overflow in the libssh2 client.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can lead to a heap buffer overflow in the libssh2 client when connecting to a malicious SSH server. Such a buffer overflow can cause crashes, memory corruption, or potentially allow an attacker to execute arbitrary code on the client system.

Since the vulnerability is exploitable remotely by a malicious SSH server, it poses a significant security risk, especially on 32-bit platforms where the integer overflow occurs.

Useful 0 Not Useful 0

Mitigation Strategies

The vulnerability affects libssh2 versions up to and including 1.11.1. To mitigate this vulnerability, you should upgrade libssh2 to a version later than 1.11.1 where this integer overflow issue is fixed.

Additionally, avoid connecting to untrusted or malicious SSH servers, especially on 32-bit platforms where the overflow occurs.

Useful 0 Not Useful 0