CVE-2026-92708: devalue: Cross-request process memory disclosure in devalue when `stringify` / `uneval` serialize Node Buffers

Vulnerability summary

CVE-2026-92708 is a high (CVSS 7.5) vulnerability in sveltejs devalue. EPSS estimates a 0.73% chance of exploitation in the next 30 days, higher than 54.1% of scored vulnerabilities.

Timeline

1. 18-09-2026
   PublishedVulnerability first disclosed.
2. 23-09-2026
   Last modifiedVulnerability information updated.

Description

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In versions 5.1.0 through 5.9.2, stringify and uneval functions serialize a typed array by emitting its entire backing ArrayBuffer rather than only the view, so serializing a Node Buffer, whose backing store is a process-wide shared pool, discloses up to 64 KB of unrelated process memory, including bytes from other in-flight requests. In a server-side-rendered framework such as SvelteKit or Nuxt, a public page whose load() returns a small Buffer, or that reads a small file, can therefore ship another user's request body or Authorization header in its HTML without authentication. Because this occurs during serialization, it fires on every such render and is not mitigated by the parse/unflatten prototype-pollution and denial-of-service guards, which only apply when parsing untrusted input. As a workaround, convert Node Buffer objects to Uint8Array before serialization. This issue has been fixed in version 5.9.3.

• CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
• CWE-226Sensitive Information in Resource Not Removed Before ReuseThe product releases a resource such as memory or a file so that it can be made available for reuse, but it does not clear or "zeroize" the information contained in the resource before the product performs a critical state transition or makes the resource available for reuse by other entities.