CVE-2026-46597: 
cAdvisor vulnerability analysis and mitigation

CVE-2026-46597 is a Denial of Service vulnerability in the golang.org/x/crypto package's SSH implementation, caused by an incorrectly placed cast from bytes to int in the AES-GCM packet decoder. A well-crafted input can trigger a server-side panic, crashing the affected service. All versions of golang.org/x/crypto prior to 0.52.0 are affected. The vulnerability was published on May 22, 2026, and carries a CVSS v3.1 base score of 7.5 (High) (Feedly, pkg.go.dev).

The root cause is an incorrect type conversion (CWE-704) in the AES-GCM packet decoder within the golang.org/x/crypto/ssh package, where a byte value is improperly cast to an integer. This flaw can be triggered remotely by an unauthenticated attacker who sends a specially crafted AES-GCM encoded SSH packet, causing the server process to panic and crash. No authentication or user interaction is required, and the attack complexity is low. The fix is tracked under Go issue #79561 and change list CL/781620 (pkg.go.dev, Feedly).

Successful exploitation results in a server-side panic, causing the SSH service (or any application embedding golang.org/x/crypto/ssh) to crash and become unavailable — a pure Availability impact with no Confidentiality or Integrity loss. Any Go application using the affected crypto library for SSH communication is at risk, including widely deployed tools such as rclone. The impact is limited to denial of service; there is no evidence of code execution or data exfiltration potential (Feedly, pkg.go.dev).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The EPSS score is approximately 0.018% (0.000180), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Despite the low exploitation likelihood, the unauthenticated, network-accessible attack vector and low complexity make it straightforward to trigger if a PoC were developed (Feedly).

1. Reconnaissance: Identify internet-facing services built with Go that use golang.org/x/crypto/ssh versions prior to 0.52.0 (e.g., SSH servers, rclone instances, or custom Go SSH daemons) using network scanning tools such as Shodan or Censys.
2. Craft malicious packet: Construct a specially crafted SSH packet that exploits the AES-GCM decoder's incorrect byte-to-int cast. The packet must be formatted to trigger the type conversion flaw during decoding.
3. Send packet to target: Transmit the malformed AES-GCM encoded SSH packet to the target server's SSH port (typically TCP/22 or a custom port) without requiring authentication.
4. Trigger server panic: The server's AES-GCM packet decoder processes the malformed input, encounters the incorrect cast, and panics — crashing the Go SSH service and causing a denial of service (pkg.go.dev, Feedly).

• Logs: Unexpected Go runtime panic messages (e.g., panic: runtime error: index out of range or similar) in application logs associated with the SSH service; sudden process termination events in system logs (e.g., journalctl or syslog entries showing the Go SSH process exiting abnormally).
• Network: Repeated inbound SSH connection attempts from the same source IP that result in immediate service crashes; unusual or malformed SSH handshake traffic captured via packet inspection on TCP/22 or the configured SSH port.
• Process: Unexpected restarts of Go-based SSH services or daemons (e.g., rclone serve sftp); process crash dumps or core files generated by the Go runtime in the application working directory.

The primary remediation is to upgrade the golang.org/x/crypto package to version 0.52.0 or later, which contains the corrected type cast in the AES-GCM decoder (pkg.go.dev). Downstream consumers such as rclone have already released updated versions incorporating the fix (rclone changelog). As a temporary workaround where immediate patching is not feasible, implement network-level filtering (firewall rules or security groups) to restrict SSH access to trusted IP ranges, reducing exposure to unauthenticated attackers. Monitor server logs for panic events that may indicate exploitation attempts.

The Go security team disclosed the vulnerability via the golang-announce mailing list and published an advisory under GO-2026-5013 (golang-announce). Multiple Linux distributions including openSUSE and Amazon Linux 2/2023 have issued security advisories and updated packages. The vulnerability was also discussed on the oss-security mailing list (oss-sec). Vulnerability scanners from Tenable (Nessus) and Qualys have added detection plugins, indicating broad industry awareness and rapid response.