Resource exhaustion in Sveltejs Devalue
CVE-2026-123569
The devalue package for npm before 5.6.3 can consume excessive CPU and memory when serializing sparse arrays with uneval or stringify. An attacker who manages to get a sparse array created on the server, which mainstream wire formats do not allow, and serialized there can cause a 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: 0.003 (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-33hq-fvwr-56pm (vendor-advisory)
- www.vulncheck.com/advisories/devalue-before-5.6.3-denial-of-service-via-sparse-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123569?
- CVE-2026-123569 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-2026-123569?
- High severity. CVSS v3 base score is 7.5 out of 10.