CVE-2026-27887 in spin
Summary
by MITRE • 02/26/2026
Spin is an open source developer tool for building and running serverless applications powered by WebAssembly. When Spin is configured to allow connections to a database or web server which could return responses of unbounded size (e.g. tables with many rows or large content bodies), Spin may in some cases attempt to buffer the entire response before delivering it to the guest, which can lead to the host process running out of memory, panicking, and crashing. In addition, a malicious guest application could incrementally insert a large number of rows or values into a database and then retrieve them all in a single query, leading to large host allocations. Spin 3.6.1, SpinKube 0.6.2, and `containerd-shim-spin` 0.22.1 have been patched to address the issue. As a workaround, configure Spin to only allow access to trusted databases and HTTP servers which limit response sizes.
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Analysis
by VulDB Data Team • 02/26/2026
The vulnerability described in CVE-2026-27887 affects Spin, an open source serverless application framework that operates using WebAssembly. This tool enables developers to build and execute serverless functions with high performance and portability. The core issue stems from Spin's handling of responses from external services such as databases and web servers that may return unbounded data sizes. When Spin processes these responses, it attempts to buffer the complete output before delivering it to guest applications, creating a potential memory exhaustion scenario that can lead to system crashes and service disruptions.
The technical flaw manifests when Spin encounters responses with unlimited or excessively large data payloads from connected services. This behavior creates a memory allocation vulnerability where the host process consumes increasingly large amounts of memory to accommodate the buffering process. The vulnerability is particularly concerning because it can be exploited through incremental data insertion techniques where malicious guest applications deliberately add numerous rows or values to databases before retrieving them all in a single query operation. This approach allows attackers to trigger massive memory allocations that can overwhelm the host system and cause system instability or complete failure.
The operational impact of this vulnerability extends beyond simple resource exhaustion to encompass potential denial of service conditions that can affect entire serverless environments. When the host process panics and crashes due to memory allocation failures, it can disrupt legitimate application execution and compromise the availability of services built on the Spin platform. The vulnerability affects multiple versions including Spin 3.6.1, SpinKube 0.6.2, and containerd-shim-spin 0.22.1, indicating a widespread issue that impacts various deployment configurations of the serverless framework. This type of vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" and represents a classic example of a resource exhaustion attack that can be leveraged to compromise system availability.
The mitigation strategy involves implementing strict access controls and response size limitations when configuring Spin environments. Organizations should configure Spin to only connect to trusted databases and HTTP servers that enforce response size limits, effectively preventing the exploitation of memory allocation vulnerabilities. Additionally, the patched versions mentioned in the advisory provide built-in protections against unbounded response handling, addressing the root cause of the vulnerability. This remediation approach follows security best practices outlined in the ATT&CK framework under the "Resource Exhaustion" technique category, where defensive measures focus on limiting resource consumption and implementing proper input validation to prevent malicious actors from exploiting system resource limitations.