What is CVE-2026-27125?

CVE-2026-27125 is a medium-severity vulnerability in Svelte, classified under Improperly Controlled Modification of Dynamically-Determined Object Attributes. CVSS score: 6.8/10. Published 2026-02-20.

How severe is CVE-2026-27125?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Vulnerability in Svelte

CVE-2026-27125

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…

Vulnerability class: Mass Assignment

EPSS: 0.004 (30.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N.

Affected products

Svelte
Sveltejs Svelte — versions < 5.51.5

Weakness classification (CWE)

CWE-915 — Improperly Controlled Modification of Dynamically-Determined Object Attributes

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (Product, x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-27125?: CVE-2026-27125 is a medium-severity vulnerability in Svelte, classified under Improperly Controlled Modification of Dynamically-Determined Object Attributes. CVSS score: 6.8/10. Published 2026-02-20.
How severe is CVE-2026-27125?: Medium severity. CVSS v3 base score is 6.8 out of 10.