---
id: CVE-2026-123564
title: Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays
summary: >-
  Sveltejs devalue from 1.0.0 before 5.9.3 contains a memory exhaustion flaw in
  uneval, whose generated code for sparse arrays allocates memory proportional
  to the array's declared length when evaluated. Attackers who can influence a
  very …
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-770
vendor: sveltejs
product: devalue
affected:
  - devalue >= 1.0.0 < 5.9.3
published: '2026-11-08'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T01:38:03.802Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-123564'
references:
  - url: >-
      https://github.com/sveltejs/devalue/security/advisories/GHSA-wf3x-273g-mvxv
    label: GitHub Security Advisory (GHSA-wf3x-273g-mvxv)
  - url: >-
      https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-memory-exhaustion-via-uneval-sparse-arrays
    label: >-
      VulnCheck Advisory: Sveltejs devalue before 5.9.3 Memory Exhaustion via
      uneval Sparse Arrays
tags:
  - cve.org
ingestedAt: '2026-11-08T02:43:18.661Z'
---

## Overview

Sveltejs devalue from 1.0.0 before 5.9.3 contains a memory exhaustion flaw in uneval, whose generated code for sparse arrays allocates memory proportional to the array's declared length when evaluated. Attackers who can influence a very large sparse array serialized by an application can exhaust memory in the browser or runtime evaluating the output.

## Affected

- `devalue >= 1.0.0 < 5.9.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.