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
EPSS: 0.003 (28.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
The 30-day trend appears once there are two daily scores.
Affected products
Weakness classification (CWE)
References
- github.com/sveltejs/devalue/security/advisories/GHSA-wf3x-273g-mvxv (vendor-advisory)
- www.vulncheck.com/advisories/sveltejs-devalue-before-5.9.3-memory-exhaustion-vi… (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.