CVE-2025-55303: Astro Astro Allows Unauthorized Third-party Images Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xf8x-j4p2-f749",
  "modified" : "2025-11-27T08:07:30Z",
  "published" : "2025-08-19T15:40:31Z",
  "aliases" : [ "CVE-2025-55303" ],
  "summary" : "Astro allows unauthorized third-party images in _image endpoint",
  "details" : "### Summary\n\nIn affected versions of `astro`, the image optimization endpoint in projects deployed with on-demand rendering allows images from unauthorized third-party domains to be served.\n\n### Details\n\nOn-demand rendered sites built with Astro include an `/_image` endpoint which returns optimized versions of images.\n\nThe `/_image` endpoint is restricted to processing local images bundled with the site and also supports remote images from domains the site developer has manually authorized (using the [`image.domains`](https://docs.astro.build/en/reference/configuration-reference/#imagedomains) or [`image.remotePatterns`](https://docs.astro.build/en/reference/configuration-reference/#imageremotepatterns) options).\n\nHowever, a bug in impacted versions of `astro` allows an attacker to bypass the third-party domain restrictions by using a protocol-relative URL as the image source, e.g. `/_image?href=//example.com/image.png`.\n\n### Proof of Concept\n\n1. Create a new minimal Astro project (`astro@5.13.0`).\n\n2. Configure it to use the Node adapter (`@astrojs/node@9.1.0` — newer versions are not impacted):\n\n   ```js\n   // astro.config.mjs\n   import { defineConfig } from 'astro/config';\n   import node from '@astrojs/node';\n\n   export default defineConfig({\n   \tadapter: node({ mode: 'standalone' }),\n   });\n   ```\n\n3. Build the site by running `astro build`.\n\n4. Run the server, e.g. with `astro preview`.\n\n5. Append `/_image?href=//placehold.co/600x400` to the preview URL, e.g. <http://localhost:4321/_image?href=//placehold.co/600x400>\n\n6. The site will serve the image from the unauthorized `placehold.co` origin.\n\n### Impact\n\nAllows a non-authorized third-party to create URLs on an impacted site’s origin that serve unauthorized image content.\nIn the case of SVG images, this could include the risk of cross-site scripting (XSS) if a user followed a link to a maliciously crafted SVG.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "astro"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0-alpha.0"
      }, {
        "fixed" : "5.13.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@astrojs/node"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.1.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 9.1.0"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "astro"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.16.19"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.16.18"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/withastro/astro/security/advisories/GHSA-xf8x-j4p2-f749"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-55303"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/withastro/astro/commit/4d16de7f95db5d1ec1ce88610d2a95e606e83820"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/withastro/astro"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-08-19T15:40:31Z",
    "nvd_published_at" : "2025-08-19T19:15:36Z"
  }
}