CVE-2026-27887 is a resource exhaustion vulnerability classified under CWE-770 (Allocation of Resources Without Limits or Throttling) affecting the Spin framework, an open source tool for running serverless applications powered by WebAssembly. When Spin is configured to connect to databases or web servers that can return responses of unbounded size—such as large database tables or extensive HTTP content—Spin may attempt to buffer the entire response before passing it to the guest application. This buffering can lead to excessive memory consumption on the host, causing the Spin process to panic and crash, resulting in denial of service. Furthermore, a malicious guest application can exacerbate this by incrementally inserting large volumes of data into a database and then retrieving all of it in a single query, forcing large memory allocations on the host. This vulnerability affects Spin versions prior to 3.6.1, SpinKube 0.6.2, and containerd-shim-spin 0.22.1, all of which have been patched to address the issue. The CVSS 4.0 score is 6.9 (medium severity), reflecting network attack vector, low attack complexity, partial privileges required, and user interaction needed. No known exploits have been reported in the wild. The root cause is the lack of limits or throttling on resource allocation when handling large or unbounded responses, which is a common issue in serverless and containerized environments where resource isolation is critical. The recommended workaround is to configure Spin to only allow connections to trusted databases and HTTP servers that enforce response size limits, thereby preventing unbounded memory consumption.

The primary impact of this vulnerability is denial of service (DoS) due to host process crashes caused by memory exhaustion. Organizations running serverless applications with Spin that connect to untrusted or large data sources risk service instability and outages. This can disrupt business operations, degrade user experience, and potentially cause cascading failures in dependent services. Attackers with limited privileges and requiring user interaction can exploit this to degrade availability, which may be leveraged as part of a larger attack chain. In environments where Spin is used for critical workloads or multi-tenant deployments, the risk of resource exhaustion can lead to broader service disruptions and increased operational costs. Although no direct confidentiality or integrity impacts are indicated, the availability impact alone can be significant, especially for organizations relying on Spin for scalable serverless infrastructure.

1. Upgrade all Spin components (Spin, SpinKube, containerd-shim-spin) to the latest patched versions (Spin 3.6.1 or later, SpinKube 0.6.2 or later, containerd-shim-spin 0.22.1 or later) to ensure the vulnerability is fixed. 2. Restrict Spin’s network access to only trusted databases and HTTP servers that enforce strict response size limits to prevent unbounded data retrieval. 3. Implement application-level throttling and query limits on databases accessed by Spin to prevent large data dumps in single queries. 4. Monitor memory usage of Spin host processes and set resource limits or alerts to detect abnormal consumption patterns early. 5. Employ runtime protections such as container resource limits (memory cgroups) to contain potential crashes and prevent host-wide impact. 6. Review guest application code and deployment policies to prevent malicious or poorly designed applications from generating large data sets. 7. Conduct regular security audits and penetration testing focused on resource exhaustion scenarios in serverless environments. 8. Educate developers and operators about the risks of unbounded data buffering and the importance of response size controls in serverless frameworks.