CVE-2026-123564

Description

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.

Overview

State: PUBLISHED
Assigner (CNA): VulnCheck
CVSS severity: HIGH
CVSS score: 8.7 / 10
CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Effective score: 8.7 / 10 HIGH source: CNA overview
CWE(s): CWE-770
Reserved: 2026-11-06
Published: 2026-11-08 01:38 UTC
Last updated: 2026-11-08 01:38 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/123xxx/CVE-2026-123564.json
Linked Threat: CVE-2026-123564 — Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-119449

EUVD enrichment is queued; refresh the page in a few seconds.

Affected products (1)

Vendor	Product	Versions	Platforms
sveltejs	devalue	`1.0.0` (affected), `5.9.3` (unaffected)	—

Vendor references (2)

References embedded in the original CVE record by the assigning CNA.

GitHub Security Advisory (GHSA-wf3x-273g-mvxv) vendor-advisory
VulnCheck Advisory: Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays third-party-advisory

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

October 2026 Critical Patch Update Released | security

web:blogs.oracle.com

For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.

2026-11-08 10:24 UTC
CVE Database Search & Remediation Guidance

web:cvedatabase.com

Search and analyze CVE vulnerabilities with instant access to CVSS scores, affected products, and remediation guidance.

2026-11-08 10:24 UTC
CVE Vulnerabilities 2026: Critical Flaws & Fixes Hub

web:cyberupdates365.com

Track critical CVE vulnerabilities 2026 with verified enterprise patch guides. Fix zero-days across VMware, WordPress, Windows, and cloud infrastructure.

2026-11-08 10:24 UTC
Patch Tuesday Tracker

web:patchtuesday.istwpro.com

Countdown to the next Microsoft Patch Tuesday, every CVE in the current release, and three years of history from the MSRC Security Update Guide.

2026-11-08 10:24 UTC
Microsoft Patch Tracker (November 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-11-08 10:24 UTC
ArcGIS Server Security 2026 Update 2 Patch - Esri Support

web:support.esri.com

This patch deals specifically with the issues listed below under Issues addressed with this patch . As part of the patch installation, the ArcGIS Server service is stopped and restarted. The restart may take several minutes depending on the number of services published on the ArcGIS Server site. This patch can be uninstalled as outlined in the Uninstalling this patch on Windows and Uninstalling ...

2026-11-08 10:24 UTC
ArcGIS Server Security 2026 Update 4 Patch - Esri Support

web:support.esri.com

The issues resolved by these patches are listed in the Issues addressed with this patch section below. As part of the patch installation, the ArcGIS Server service is stopped and restarted. The restart may take several minutes depending on the number of services published on the ArcGIS Server site. This patch can be uninstalled as outlined in the Uninstalling this patch on Windows and ...

2026-11-08 10:24 UTC
SAP Security Patch Day - October 2026

web:support.sap.com

On 13 th of October 2026 , SAP security patch day saw the release of 16 new security notes and 4 GitHub security advisories. There are 2 updates to previously released security notes.

2026-11-08 10:24 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-11-08 10:24 UTC
Oracle Critical Security Patch Update Advisory - September 2026

web:www.oracle.com

Prior Critical Patch Update and Critical Security Patch Update advisories should be reviewed for information regarding earlier published security patches. Refer to Critical Patch Updates, Critical Security Patch Updates, Security Alerts and Bulletins for information about Oracle Security advisories.

2026-11-08 10:24 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-123564.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/devalue",
          "product": "devalue",
          "vendor": "sveltejs",
          "versions": [
            {
              "lessThan": "5.9.3",
              "status": "affected",
              "version": "1.0.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.9.3",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:svelte:devalue:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.9.3",
                  "versionStartIncluding": "1.0.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
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          "lang": "en",
          "type": "remediation developer",
          "value": "elliott-with-the-longest-name-on-github"
        }
      ],
      "datePublic": "2026-09-18T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
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        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
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            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
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            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "cvssV3_1": {
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            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-08T01:38:03.802Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "GitHub Security Advisory (GHSA-wf3x-273g-mvxv)",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/sveltejs/devalue/security/advisories/GHSA-wf3x-273g-mvxv"
        },
        {
          "name": "VulnCheck Advisory: Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-memory-exhaustion-via-uneval-sparse-arrays"
        }
      ],
      "title": "Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays",
      "x_generator": {
        "engine": "vulncheck-endgame"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-123564",
    "datePublished": "2026-11-08T01:38:03.802Z",
    "dateReserved": "2026-11-06T00:50:45.483Z",
    "dateUpdated": "2026-11-08T01:38:03.802Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}