{
  "cveId": "CVE-2026-18540",
  "url": "https://patchblox.com/security/cve/CVE-2026-18540",
  "summary": "CVE-2026-18540 is fixed in 21 products on 1 platform, first by DEBIAN-CVE-2026-18540, released September 10, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "undici vulnerable to downstream response splitting via retry interceptor",
  "description": "undici\u0027s retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response\u0027s status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.",
  "published": "2026-09-04T18:17:50Z",
  "severity": "Low",
  "cvss": 3.7,
  "cvssVector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
  "cwe": "Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
  "epss": 0.00309,
  "epssPercentile": 0.23903,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18540",
  "fixes": [
    {
      "platform": "linux",
      "product": "node-undici",
      "release": "Debian 14",
      "fixedVersion": "8.10.2\u002Bdfsg\u002B~cs3.2.2-1",
      "fix": "DEBIAN-CVE-2026-18540",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-18540",
      "released": "2026-09-10T12:12:19Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-debugsource",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-devel",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-docs",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-full-i18n",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-libs",
      "release": "amzn 2023",
      "fixedVersion": "1:22.23.3-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
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      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs22-npm",
      "release": "amzn 2023",
      "fixedVersion": "1:10.9.9-1.22.23.3.1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3277",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3277",
      "released": "2026-11-07T01:06:07Z"
    },
    {
      "platform": "linux",
      "product": "nodejs24",
      "release": "amzn 2023",
      "fixedVersion": "1:24.21.0-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
    },
    {
      "platform": "linux",
      "product": "nodejs24-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1:24.21.0-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
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      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
    },
    {
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      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
    },
    {
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      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
    },
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      "release": "amzn 2023",
      "fixedVersion": "1:24.21.0-1.amzn2023.0.1",
      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
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      "fix": "ALAS2023-2026-3107",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3107",
      "released": "2026-09-28T09:00:00Z"
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      "fix": "ALAS2023-2026-3107",
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      "released": "2026-09-28T09:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}