Unbounded memory consumption in golang.org/x/crypto/ssh

Vulnerability

Description

CVE-2025-58181 is a denial-of-service vulnerability in SSH servers that parse GSSAPI authentication requests. The root cause is that the server does not validate the number of mechanisms specified in the request, allowing an attacker to craft a request with an arbitrarily large number of mechanisms, leading to unbounded memory consumption [1][4].

Exploitation

An attacker can exploit this vulnerability by sending a specially crafted GSSAPI authentication request to a vulnerable SSH server. No authentication is required, and the attack can be performed over the network. The server will attempt to allocate memory for each mechanism listed in the request, potentially exhausting available memory [2][4].

Impact

Successful exploitation results in a denial-of-service condition where the SSH server consumes excessive memory, potentially causing the server to crash or become unresponsive. This can disrupt legitimate SSH connections and services [1][4].

Mitigation

The vulnerability is fixed in golang.org/x/crypto version v0.45.0. Users should update their dependencies to this version or later. The Go security team has released patches and advisories [2][3][4].