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
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-33hq-fvwr-56pm) (vendor-advisory)
- VulnCheck Advisory: Devalue before 5.6.3 Denial of Service via Sparse Array Serialization (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.