Denial of Service Vulnerability in Devalue by SvelteJS
CVE-2026-123562

8.7HIGH

Key Information:

Vendor

Sveltejs

Status
Devalue
Vendor
CVE Published:
8 November 2026

What is CVE-2026-123562?

The Devalue package in SvelteJS versions prior to 5.9.3 is susceptible to a denial of service due to an unhandled promise rejection in the stringifyAsync function. When attempting to serialize multiple promises, if a later promise fails before an earlier one completes, it can lead to an unhandled rejection that might terminate the Node.js process. This vulnerability may be exploited by an attacker who can manipulate the order or timing of promise resolutions, potentially causing significant disruption to applications dependent on Devalue.

Affected Version(s)

devalue 5.8.0 < 5.9.3

devalue 5.9.3

References

https://github.com/sveltejs/devalue/security/advisories/G...
vendor-advisory
https://www.vulncheck.com/advisories/devalue-5.8.0-before...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

elliott-with-the-longest-name-on-github
.