CVE-2026-123566
📛 CVE Title
Devalue before 5.9.3 CPU Amplification Denial of Service via uneval
Description
Sveltejs devalue before 5.9.3 contains a denial of service vulnerability that allows attackers to cause CPU amplification by supplying sparse arrays to uneval. Attackers who influence sparse values passed to uneval can force synchronous work proportional to the declared array length, blocking the event loop.
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-400 - 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-2026-123566.json
- Linked Threat
- CVE-2026-123566 — Devalue before 5.9.3 CPU Amplification Denial of Service via uneval
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-2026-119451
EUVD enrichment is queued; refresh the page in a few seconds.
Affected products (1)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| sveltejs | devalue |
0 (affected),
5.9.3 (unaffected)
|
— |
Vendor references (2)
References embedded in the original CVE record by the assigning CNA.
- GitHub Security Advisory (GHSA-hx4r-w6wj-j8fg) vendor-advisory
- VulnCheck Advisory: Devalue before 5.9.3 CPU Amplification Denial of Service via uneval 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.
-
web:malware.news
Google specifically recommends sandboxing agentic workloads and moving to risk-based triage. How to Fix and Prioritize CVE 2026 Vulnerabilities Fix CVE-2026 vulnerabilities by patching exploited and internet-exposed systems first, applying vendor mitigations where a patch lags, and ranking everything else using CVSS, EPSS, and KEV together.
2026-11-08 10:24 UTC -
web:sec.cloudapps.cisco.com
As part of Cisco's ongoing commitment to proactive security and product quality, engineering teams conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. These vulnerabilities were found during internal testing and are not known to be actively exploited. To assist customers in patching ...
2026-11-08 10:24 UTC -
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 -
web:support.apple.com
This document describes the security content of iOS 26.6 and iPadOS 26.6.
2026-11-08 10:24 UTC -
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 Portal for ArcGIS service is stopped and restarted. The restart may take several minutes depending on the number of items on the enterprise deployment. As a best practice, clear the browser cache and re-launch the browser after installing the patch . This ...
2026-11-08 10:24 UTC -
web:trust.barracuda.com
Barracuda immediately initiated a comprehensive remediation process and released security patches for affected products. Customers should review the affected products and remediation guidance below, ensure their systems are running the latest firmware version, and have all security patches applied.
2026-11-08 10:24 UTC -
web:www.bleepingcomputer.com
Today is Microsoft's October 2026 Patch Tuesday, with security updates addressing a record-breaking 1,411 flaws, including one actively exploited and two publicly disclosed zero-day vulnerabilities.
2026-11-08 10:24 UTC -
web:www.microsoft.com
If you can't patch immediately: Apply the PHP project's interim mitigations and the Azure WAF protections. Note: This reduces exposure but doesn't fix the underlying vulnerabilities.
2026-11-08 10:24 UTC -
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 -
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-2026-123566.json.
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"packageURL": "pkg:npm/devalue",
"product": "devalue",
"vendor": "sveltejs",
"versions": [
{
"lessThan": "5.9.3",
"status": "affected",
"version": "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",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "remediation developer",
"value": "elliott-with-the-longest-name-on-github"
}
],
"datePublic": "2026-09-18T00:00:00.000Z",
"descriptions": [
{
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"value": "Sveltejs devalue before 5.9.3 contains a denial of service vulnerability that allows attackers to cause CPU amplification by supplying sparse arrays to uneval. Attackers who influence sparse values passed to uneval can force synchronous work proportional to the declared array length, blocking the event loop."
}
],
"metrics": [
{
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"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"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",
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"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
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"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"
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],
"problemTypes": [
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"descriptions": [
{
"cweId": "CWE-400",
"description": "Uncontrolled Resource Consumption",
"lang": "en",
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"providerMetadata": {
"dateUpdated": "2026-11-08T01:38:05.159Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"shortName": "VulnCheck"
},
"references": [
{
"name": "GitHub Security Advisory (GHSA-hx4r-w6wj-j8fg)",
"tags": [
"vendor-advisory"
],
"url": "https://github.com/sveltejs/devalue/security/advisories/GHSA-hx4r-w6wj-j8fg"
},
{
"name": "VulnCheck Advisory: Devalue before 5.9.3 CPU Amplification Denial of Service via uneval",
"tags": [
"third-party-advisory"
],
"url": "https://www.vulncheck.com/advisories/devalue-before-5.9.3-cpu-amplification-denial-of-service-via-uneval"
}
],
"title": "Devalue before 5.9.3 CPU Amplification Denial of Service via uneval",
"x_generator": {
"engine": "vulncheck-endgame"
}
}
},
"cveMetadata": {
"assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
"assignerShortName": "VulnCheck",
"cveId": "CVE-2026-123566",
"datePublished": "2026-11-08T01:38:05.159Z",
"dateReserved": "2026-11-06T00:53:14.312Z",
"dateUpdated": "2026-11-08T01:38:05.159Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}