CVE-2026-82260 in SvelteKit
Summary
by MITRE • 08/28/2026
SvelteKit (@sveltejs/kit) versions >=2.49.0 and <=2.52.1 with experimental remote functions (experimental.remoteFunctions) and form enabled contain a memory exhaustion vulnerability in remote form deserialization. Malformed form data can cause excessive memory allocation, crashing the server process and resulting in denial of service. Fixed in 2.52.2.
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Analysis
by VulDB Data Team • 08/28/2026
The SvelteKit framework, specifically versions ranging from 2.49.0 through 2.52.1, contains a critical vulnerability affecting its experimental remote functions feature when combined with form handling capabilities. This security flaw manifests as a memory exhaustion issue during the deserialization of incoming form data submitted to remote endpoints. The vulnerability is rooted in how the framework processes and allocates resources for malformed or excessively large payloads within this specific configuration. Because the affected code path relies on dynamic allocation without sufficient bounds checking or size validation, an attacker can exploit this behavior by sending carefully crafted requests that trigger disproportionate memory consumption relative to the input size.
From a technical perspective, the flaw allows for a denial of service attack against servers running vulnerable versions of SvelteKit with remote functions enabled. When a malicious actor submits form data designed to abuse the deserialization logic, the server attempts to allocate excessive amounts of memory to process the request. This uncontrolled resource consumption can quickly deplete available system resources, leading to the termination or crash of the Node.js process hosting the application. The impact is severe as it results in complete service unavailability for legitimate users until the affected instance is restarted or the malicious traffic subsides and garbage collection eventually recovers some memory, though repeated attacks will likely cause sustained outages.
This vulnerability aligns with CWE-400, which describes Uncontrolled Resource Consumption, specifically focusing on how improper handling of input can lead to resource exhaustion. In terms of offensive security frameworks, this exploit maps directly to the MITRE ATT&CK technique T1498, Network Denial of Service, where an adversary aims to disrupt service availability by overwhelming system resources rather than compromising data integrity or confidentiality. The attack vector is primarily network-based and requires interaction with a form-enabled endpoint that utilizes remote functions, making it accessible to any user who can submit HTTP requests to the vulnerable application endpoints.
Mitigation strategies for this vulnerability are straightforward but require immediate action from development teams maintaining affected applications. The primary remediation step is to upgrade SvelteKit to version 2.52.2 or later, where the deserialization logic has been patched to include proper validation and limits on memory allocation during form processing. For organizations unable to patch immediately due to dependency constraints, temporary workarounds may involve disabling experimental remote functions if they are not strictly necessary for business operations, thereby removing the vulnerable code path from execution. Additionally implementing rate limiting and input size restrictions at the reverse proxy or load balancer level can help mitigate the impact by preventing excessively large payloads from reaching the application layer in high volumes.