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CVE-2026-42570— Svelte devalue: DoS via sparse array deserialization

Quick assessment

Affected
sveltejs devalue
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

devalue是Svelte开源的一个增强的JavaScript对象序列化库。 devalue 5.6.3版本至5.8.1之前版本存在安全漏洞，该漏洞源于反序列化稀疏数组时内存分配过多，可能导致过度内存消耗。

CVSS 7.5 · High EPSS 0.72% · P52

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 1

VendorProduct Version RangeStatus
sveltejs devalue >= 5.6.3, < 5.8.1 affected
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I. Basic Information for CVE-2026-42570

Vulnerability Information
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Vulnerability Title
Svelte devalue: DoS via sparse array deserialization
Source: CVE Program / CVE List V5
Vulnerability Description
Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. From version 5.6.3 to before version 5.8.1, devalue.parse could, due to quirks in some JavaScript engines, be convinced to allocate much more memory than was needed when deserializing sparse arrays, leading to excessive memory consumption. This issue has been patched in version 5.8.1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
devalue 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
devalue是Svelte开源的一个增强的JavaScript对象序列化库。 devalue 5.6.3版本至5.8.1之前版本存在安全漏洞，该漏洞源于反序列化稀疏数组时内存分配过多，可能导致过度内存消耗。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
sveltejs devalue >= 5.6.3, < 5.8.1 -

II. Public POCs for CVE-2026-42570

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 8106 chars
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III. Intelligence Information for CVE-2026-42570

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Patches & Fixes for CVE-2026-42570 (1)

Vendor Advisories for CVE-2026-42570 (1)

Other References for CVE-2026-42570 (1)

Same Patch Batch · sveltejs · 2026-06-09 · 4 CVEs total

CVE-2026-42567 Svelte: ReDoS in `<svelte:element>` Tag Validation
CVE-2026-42573 Svelte: XSS via DOM Clobbering of Internal Framework State
CVE-2026-42599 Cross-site scripting via spread attributes in Svelte SSR

IV. Related Vulnerabilities

Same product: devalue
Same vendor: sveltejs
Same weakness: CWE-770

V. Comments for CVE-2026-42570

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