CVE-2026-123566 PUBLISHED

Devalue before 5.9.3 CPU Amplification Denial of Service via uneval

Assigner: VulnCheck
Reserved: 06.11.2026 Published: 08.11.2026 Updated: 08.11.2026

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.

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
CVSS Score: 8.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 7.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	sveltejs
Product	devalue
Versions	Default: unaffected affected from 0 to 5.9.3 (excl.) Version 5.9.3 is unaffected

CVE-2026-123566 PUBLISHED

Devalue before 5.9.3 CPU Amplification Denial of Service via uneval

Metrics

Product Status

Credits

References

Problem Types