CVE-2026-30226CWE-1321

devalue has prototype pollution in devalue.parse and devalue.unflatten

Medium · published March 11, 2026

CVSS v4.0
6.3
EPSS
1%
Percentile
45.5
In the wild
Unconfirmed
What it is

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

The record
Technical detail
CVSS v4.0
6.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
EPSS
0.00554 · 45.5th percentile
Weakness
CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Published
2026-03-11T17:47Z
EPSS history
Timeline
  • 11 MAR 17:47Z
    devalue has prototype pollution in devalue.parse and devalue.unflatten
    cvelistv5