CVE-2025-47913 is a vulnerability classified under CWE-703 (Improper Handling of Exceptional Conditions) found in the golang.org/x/crypto/ssh/agent package, a widely used Go library for SSH agent communication. The flaw occurs when an SSH client receives an SSH_AGENT_SUCCESS message while expecting a typed response; instead of handling this gracefully, the client panics and terminates prematurely. This behavior results from inadequate validation and error handling in the SSH agent client code, causing a denial-of-service (DoS) condition by crashing the client process. The vulnerability affects all versions of the package as indicated, with no patches currently available. The CVSS 3.1 score of 7.5 reflects a high severity due to the network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but a high impact on availability (A:H). Although no known exploits are reported in the wild, the vulnerability could be exploited remotely by an attacker capable of injecting or manipulating SSH agent responses, causing client crashes and disrupting automated or manual SSH operations. This is particularly critical in environments relying on Go-based SSH clients for secure communications and automation.

For European organizations, the primary impact is denial of service through unexpected termination of SSH client processes, which can disrupt secure shell sessions, automated deployment pipelines, and remote management tasks. This can lead to operational downtime, loss of productivity, and potential delays in critical infrastructure management or software development workflows. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely; however, availability disruptions can have cascading effects, especially in sectors like finance, telecommunications, energy, and government services that rely heavily on SSH for secure remote access. The lack of required privileges or user interaction means attackers can exploit this vulnerability remotely and silently, increasing the risk of widespread disruption. Organizations using Go-based tooling or custom SSH clients embedding this package are particularly vulnerable. The absence of known exploits provides a window for proactive mitigation but also means attackers may develop exploits in the future.

Organizations should monitor for official patches or updates from the golang.org/x/crypto project and apply them promptly once available. In the interim, developers should implement additional error handling around SSH agent responses to catch unexpected message types and prevent client panics. Employing SSH client wrappers or middleware that validate and sanitize agent responses can reduce risk. Network-level controls to restrict or monitor SSH agent communication may help detect anomalous messages indicative of exploitation attempts. Additionally, organizations should audit their Go-based SSH client usage to identify affected versions and consider temporary workarounds such as disabling SSH agent forwarding where feasible. Incorporating robust logging and alerting on SSH client crashes will aid in early detection of exploitation attempts. Finally, educating development and operations teams about this vulnerability ensures preparedness for patch deployment and incident response.