CVE-2026-27125
Svelte SSR attribute spreading includes inherited properties from prototype chain
- State
- Published
- Severity
- 5.3 Medium
- Published
- Feb 20, 2026
- Updated
- Feb 25, 2026
- Reserved
- Feb 17, 2026
Description
svelte performance oriented web framework. Prior to 5.51.5, in server-side rendering, attribute spreading on elements (e.g. <div {...attrs}>) enumerates inherited properties from the object's prototype chain rather than only own properties. In environments where Object.prototype has already been polluted — a precondition outside of Svelte's control — this can cause unexpected attributes to appear in SSR output or cause SSR to throw errors. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.3 Medium | CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N | GitHub_M |
Weaknesses
- CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes
Affected Products
| Product | Versions |
|---|---|
sveltesveltejs |
|
References
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