CVE-2026-42570Network attack vector

Host-process crash via eager sparse-array allocation

Published Jun 9, 2026 · Updated Jun 9, 2026

Denial of service in Svelte devalue 5.6.3 through 5.8.0 allows remote attackers to crash a host process via sparse-array input. devalue.parse passes each untrusted sparse-array length to new Array(), causing V8 to eagerly allocate a contiguous backing store far larger than the payload. An application must pass attacker-controlled serialized data to the parser; repeated claimed lengths can exhaust memory without disclosing or altering data.

CVSS severityUnavailable
Unscored
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Svelte devalue 5.6.3 through 5.8.0 allows remote attackers to crash a host process via sparse-array input. devalue.parse passes each untrusted sparse-array length to new Array(), causing V8 to eagerly allocate a contiguous backing store far larger than the payload. An application must pass attacker-controlled serialized data to the parser; repeated claimed lengths can exhaust memory without disclosing or altering data.

The record

CVE
CVE-2026-42570
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
Svelte
Product
devalue
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 5.6.3, < 5.8.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · devalueversion=>= 5.6.3, < 5.8.1

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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