CVE-2025-47913 is a security vulnerability identified in the golang.org/x/crypto SSH agent implementation, specifically within the ssh/agent package. The issue arises from improper handling of exceptional conditions (classified under CWE-703) where an SSH client expects a typed response but instead receives an SSH_AGENT_SUCCESS message. This unexpected message causes the client to panic, leading to an early termination of the client process. The vulnerability effectively results in a denial-of-service (DoS) condition against SSH clients that rely on this package for SSH agent communication. The flaw affects all versions of the golang.org/x/crypto/ssh/agent package as indicated by the affectedVersions field. No CVSS score has been assigned yet, and no known exploits have been reported in the wild. The vulnerability does not require authentication or user interaction to trigger, making it relatively easy to exploit in environments where an attacker can send crafted SSH agent messages. The root cause is the lack of robust error handling for unexpected message types from the SSH agent, which violates secure coding practices for handling exceptional conditions. This can disrupt automated systems, developer workflows, and any infrastructure components that depend on Go-based SSH clients or tools embedding this package. Since golang.org/x/crypto is a widely used cryptographic library in the Go ecosystem, the impact could be broad, especially in environments with heavy use of Go for infrastructure tooling and automation. The absence of a patch link suggests that a fix is pending or under development. Organizations should monitor updates from the Go project and prepare to apply patches promptly once available.

The primary impact of CVE-2025-47913 is denial of service due to client process crashes when unexpected SSH agent messages are received. For European organizations, this can disrupt critical development and operational workflows that rely on Go-based SSH clients or automation tools using the golang.org/x/crypto/ssh/agent package. This may lead to temporary loss of access to remote systems, delays in deployment pipelines, and interruptions in secure communications. While confidentiality and integrity are not directly compromised, the availability impact can affect business continuity and operational efficiency. Sectors with high reliance on automated SSH operations, such as financial services, telecommunications, and technology companies, may experience more pronounced effects. Additionally, organizations using containerized or cloud-native environments with Go tooling could face cascading failures if the vulnerability is triggered at scale. The lack of authentication requirement for triggering the vulnerability increases the risk surface, especially in environments where attackers can inject or intercept SSH agent messages. However, the absence of known exploits in the wild currently limits immediate widespread impact.

1. Monitor official Go project repositories and security advisories for patches addressing CVE-2025-47913 and apply updates promptly once released. 2. Implement robust input validation and error handling in any custom tooling or wrappers around the golang.org/x/crypto/ssh/agent package to gracefully handle unexpected SSH agent messages and prevent client panics. 3. Restrict network access to SSH agent sockets and communication channels to trusted entities only, minimizing the risk of malicious message injection. 4. Employ runtime monitoring and alerting for unexpected SSH client crashes to detect potential exploitation attempts early. 5. For critical systems, consider isolating or sandboxing SSH client processes to limit the impact of crashes on broader system stability. 6. Review and update incident response plans to include scenarios involving SSH client denial-of-service conditions. 7. Educate developers and DevOps teams about this vulnerability to ensure awareness and prompt remediation in development pipelines.