Resource exhaustion in Sveltejs Devalue
CVE-2026-123564
Sveltejs devalue from 1.0.0 before 5.9.3 contains a memory exhaustion flaw in uneval, whose generated code for sparse arrays allocates memory proportional to the array's declared length when evaluated. Attackers who can influence a very large sparse array serialized by an application can exhaust memory in the browser or runtime evaluating the output.
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-wf3x-273g-mvxv) (vendor-advisory)
- VulnCheck Advisory: Sveltejs devalue before 5.9.3 Memory Exhaustion via uneval Sparse Arrays (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123564?
- CVE-2026-123564 is a high-severity vulnerability in Sveltejs Devalue, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-11-08.
- How severe is CVE-2026-123564?
- High severity. CVSS v3 base score is 7.5 out of 10.