CVE-2025-58181: 
cAdvisor vulnerability analysis and mitigation

CVE-2025-58181 is a denial-of-service vulnerability in the Go golang.org/x/crypto/ssh package where SSH servers parsing GSSAPI authentication requests fail to validate the number of mechanisms specified in the request, allowing an unauthenticated attacker to cause unbounded memory consumption. It affects all versions of golang.org/x/crypto prior to 0.45.0. The vulnerability was published on November 19, 2025, with a fix released the same day. It carries a CVSS v3.1 base score of 5.3 (Medium) (GitHub Advisory, Feedly).

The root cause is classified as CWE-770 (Allocation of Resources Without Limits or Throttling). When an SSH server built using the Go golang.org/x/crypto/ssh library processes a GSSAPI authentication request, it does not impose any upper bound on the number of authentication mechanisms listed in the request. An unauthenticated remote attacker can craft a malicious GSSAPI authentication message containing an arbitrarily large number of mechanism entries, causing the server to allocate unbounded memory as it parses the list. No authentication or special privileges are required, and the attack can be performed over a standard network connection to any exposed SSH port. The fix is tracked in the Go issue tracker as issue #76363 and implemented via code change CL 721961 (GitHub Advisory, Go Vuln DB).

Successful exploitation results in excessive memory consumption on the affected SSH server, which can degrade performance or crash the service entirely, constituting a denial-of-service condition. There is no impact on confidentiality or integrity — the vulnerability is limited to availability. Any application or service using the Go golang.org/x/crypto/ssh package as an SSH server with GSSAPI authentication enabled is potentially affected, including a broad range of downstream products such as IBM Cloud Pak for Business Automation, IBM Business Automation Workflow, IBM Guardium Data Security Center, EDB PGAI Hybrid Management, and various Oracle products (GitHub Advisory, Feedly).

No public proof-of-concept exploit code is known to exist, and there is no evidence of active in-the-wild exploitation at this time (Feedly). The EPSS score is approximately 0.082%, indicating a low near-term probability of exploitation. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been reported. Despite the low exploitation evidence, the attack requires no authentication and no user interaction, making it trivially triggerable against any exposed vulnerable SSH server.

1. Reconnaissance: Identify internet-facing SSH servers running applications built with golang.org/x/crypto versions prior to 0.45.0 using network scanning tools (e.g., Shodan, Censys, nmap). Look for services advertising GSSAPI authentication support in their SSH handshake.
2. Initiate SSH connection: Establish a TCP connection to the target SSH port (default: 22) and begin the SSH handshake.
3. Craft malicious GSSAPI authentication request: During the authentication phase, send a specially crafted SSH SSH_MSG_USERAUTH_REQUEST message of type gssapi-with-mic containing an abnormally large number of GSSAPI mechanism OIDs in the mechanism list field.
4. Trigger unbounded memory allocation: The vulnerable server parses the mechanism list without enforcing any limit, allocating memory for each entry. Sending a sufficiently large number of mechanisms causes the server process to exhaust available memory.
5. Achieve denial of service: The SSH server process crashes or becomes unresponsive due to memory exhaustion, denying service to legitimate users (GitHub Advisory, Go Vuln DB).

• Network: Repeated inbound TCP connections to SSH port (22 or custom) from the same or rotating source IPs that do not complete a full authentication handshake; unusually large SSH authentication request packets observed in network captures.
• Logs: SSH server logs showing a high volume of GSSAPI authentication attempts from a single or small set of source addresses; authentication failures or abrupt connection terminations during the GSSAPI negotiation phase.
• Process/System: Sudden spike in memory usage by the SSH server process (e.g., sshd or Go-based SSH daemon) leading to OOM (out-of-memory) killer events; system logs (/var/log/syslog, dmesg) showing OOM kill events targeting the SSH service process.
• Availability: Unexpected SSH service crashes or restarts correlated with inbound connection attempts from external sources.

The primary remediation is to upgrade golang.org/x/crypto to version 0.45.0 or later, which includes the fix for this vulnerability (GitHub Advisory, Go Vuln DB). Downstream product users should apply vendor-specific patches: IBM has released iFixes for IBM Cloud Pak for Business Automation, IBM Business Automation Workflow, IBM Guardium Data Security Center, EDB PGAI Hybrid Management, IBM Db2 on Cloud Pak for Data, and IBM Storage Defender Copy Data Management (IBM Advisory); Oracle addressed this in the April 2026 Critical Patch Update (Oracle CPU). As a temporary workaround where patching is not immediately possible, restrict SSH access to trusted IP ranges using firewall rules or network access controls to limit exposure of the vulnerable service.

The Go security team disclosed the vulnerability via the golang-announce mailing list and published a corresponding entry in the Go vulnerability database (GO-2025-4134) on the same day as the CVE publication (Go Vuln DB). The vulnerability was picked up by Golang Weekly (issue 580) and received coverage across Linux distribution security channels including openSUSE, Ubuntu, Amazon Linux, and FreeBSD, reflecting broad ecosystem impact due to the widespread use of the golang.org/x/crypto library. No significant controversy or notable researcher commentary beyond standard disclosure has been observed.