SvelteJS devalue up to 5.9.2 Serialization stringify/uneval information disclosure

Summaryinfo

A vulnerability classified as problematic has been found in SvelteJS devalue up to 5.9.2. This issue affects the function stringify/uneval of the component Serialization. Performing a manipulation results in information disclosure. This vulnerability was named CVE-2026-92708. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in SvelteJS devalue up to 5.9.2. This affects the function stringify/uneval of the component Serialization. The manipulation with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-92708 since 09/16/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 5.9.3 eliminates this vulnerability.

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Productinfo

Vendor

• SvelteJS

Name

• devalue

Version

• 5.9.0
• 5.9.1
• 5.9.2

Website

• Product: https://github.com/sveltejs/devalue/

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