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CVE-2026-123566

7.5, high

Sveltejs devalue Uncontrolled Resource Consumption Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
n/a
Exploitation
No public evidence
Published
8 Nov 2026today

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.

Details

Vendor
Sveltejs
Product
devalue
Weakness
CWE-400 (opens in a new tab)
Status
Received
Updated
8 Nov 2026
Assigner
disclosure@vulncheck.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References 2

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Sveltejs CVEs

Every Sveltejs CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-123562 devalue (sveltejs/devalue) 5.8.0 before 5.9.3 contains an unhandled promise rejection in stringifyAsync: when serializing multiple… 7.5, high
  • CVE-2026-123563 Devalue before 5.9.3 contains a validation bypass vulnerability that allows custom ArrayBuffer revivers to skip typed-array allocation… 7.5, high
  • CVE-2026-123564 Sveltejs devalue Allocation of Resources Without Limits or Throttling Vulnerability 7.5, high
  • CVE-2026-123565 Sveltejs devalue Uncontrolled Resource Consumption Vulnerability 7.5, high
  • CVE-2026-123569 Sveltejs devalue Allocation of Resources Without Limits or Throttling Vulnerability 7.5, high
  • CVE-2026-114063 Sveltejs kit Path Traversal Vulnerability EPSS 0.4% 7.5, high

Beyond this page

Is CVE-2026-123566 in your network?

This page tells you how dangerous CVE-2026-123566 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-123566 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 8 Nov 2026, not the live upstream state.