Resource exhaustion in Sveltejs Devalue
CVE-2026-123565
Sveltejs devalue before 5.9.3 contains a resource exhaustion vulnerability where repeated primitive strings cause quadratic expansion in the uneval function. Attackers can supply a small crafted payload that is parsed and then passed to uneval, producing a very large serialized string that exhausts memory or CPU.
Vulnerability class: DoS (Denial of Service)
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-mcm9-63f2-9j32) (vendor-advisory)
- VulnCheck Advisory: Devalue before 5.9.3 Quadratic Expansion Denial of Service via uneval (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123565?
- CVE-2026-123565 is a high-severity vulnerability in Sveltejs Devalue, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-11-08.
- How severe is CVE-2026-123565?
- High severity. CVSS v3 base score is 7.5 out of 10.