Vulnerability · Published Sep 16, 2026 · Assigned by GitHub_M

CVE-2026-81176Svelte devalue: DoS via malformed input

Medium 5.3

In plain English

A medium-severity resource allocation without limits in devalue from sveltejs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.5%top 56.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. Prior to 5.9.2, devalue.parse does not reject out-of-bounds indices that are greater than or equal to values.length in src/parse.js. A specially crafted untrusted payload can make the parser alternate between array representations, producing quadratic work as the payload grows and causing denial of service in applications that parse untrusted devalue data. This issue is fixed in version 5.9.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	devalue	5.9.2	GHSA-9rgm-9g3h-6x36

Affected products (as reported)

Vendor	Product	Versions
sveltejs	devalue	< 5.9.2

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

https://github.com/sveltejs/devalue/security/advisories/GHSA-9rgm-9g3h-6x36 x_refsource_CONFIRM
https://github.com/sveltejs/devalue/commit/8b2a4562c446d7c36d9d629778079a5fae4243e1 x_refsource_MISC
https://github.com/sveltejs/devalue/releases/tag/v5.9.2 x_refsource_MISC