Resource Exhaustion Vulnerability in Sveltejs Devalue Affecting Multiple Versions
CVE-2026-123565

8.7HIGH

Key Information:

Vendor

Sveltejs

Status
Devalue
Vendor
CVE Published:
8 November 2026

What is CVE-2026-123565?

The Sveltejs Devalue library prior to version 5.9.3 is susceptible to a resource exhaustion vulnerability. This flaw allows attackers to craft simple payloads that, once parsed, are passed to the uneval function. This process can lead to quadratic expansion, producing an excessively large serialized string that can potentially exhaust system memory or CPU resources, resulting in Denial of Service (DoS) conditions. It is advisable for users to upgrade to the latest version to mitigate the risks associated with this vulnerability.

Affected Version(s)

devalue 0 < 5.9.3

devalue 5.9.3

References

https://github.com/sveltejs/devalue/security/advisories/G...
vendor-advisory
https://www.vulncheck.com/advisories/devalue-before-5.9.3...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

elliott-with-the-longest-name-on-github
.