GHSA-CRPF-4HRX-3JRP

Vulnerability from github – Published: 2026-02-19 20:28 – Updated: 2026-02-19 20:28
VLAI?
Summary
Svelte SSR attribute spreading includes inherited properties from prototype chain
Details

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.

Severity ?
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
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.51.4"
      },
      "package": {
        "ecosystem": "npm",
        "name": "svelte"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.51.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27125"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-915"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-19T20:28:49Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "In server-side rendering, attribute spreading on elements (e.g. `\u003cdiv {...attrs}\u003e`) enumerates inherited properties from the object\u0027s prototype chain rather than only own properties. In environments where `Object.prototype` has already been polluted \u2014 a precondition outside of Svelte\u0027s control \u2014 this can cause unexpected attributes to appear in SSR output or cause SSR to throw errors. Client-side rendering is not affected.",
  "id": "GHSA-crpf-4hrx-3jrp",
  "modified": "2026-02-19T20:28:49Z",
  "published": "2026-02-19T20:28:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sveltejs/svelte/security/advisories/GHSA-crpf-4hrx-3jrp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sveltejs/svelte/commit/73098bb26c6f06e7fd1b0746d817d2c5ee90755f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sveltejs/svelte"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sveltejs/svelte/releases/tag/svelte@5.51.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Svelte SSR attribute spreading includes inherited properties from prototype chain"
}


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