Vulnerability in Sveltejs Devalue
CVE-2026-123563
Devalue before 5.9.3 contains a validation bypass vulnerability that allows custom ArrayBuffer revivers to skip typed-array allocation checks in the parse function. Attackers can supply very small crafted input processed by a malformed ArrayBuffer reviver to allocate massive ArrayBuffers, causing memory exhaustion and 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
EPSS: 0.004 (31.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 31.7% 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-r9w8-h9r3-54w4 (vendor-advisory)
- www.vulncheck.com/advisories/devalue-before-5.9.3-typed-array-allocation-valida… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123563?
- CVE-2026-123563 is a high-severity vulnerability in Sveltejs Devalue, classified under CWE-789. CVSS score: 7.5/10. Published 2026-11-08.
- How severe is CVE-2026-123563?
- High severity. CVSS v3 base score is 7.5 out of 10.