node-undici — security advisory

{
  "id": "ddfd47777afa50e6b54a931f62fc4c0d96c34b3e2476c0607817f60c95a8e5ef",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-18540",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-18540",
    "summary": "undici's 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's 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.",
    "evidence": "osv:UBUNTU-CVE-2026-18540",
    "products": [
      {
        "name": {
          "value": "node-undici",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "5.22.1+dfsg1+~cs20.10.10.2-1ubuntu1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "5.26.3+dfsg1+~cs23.10.12-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "node-undici",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "7.18.2+dfsg+~cs3.2.0-1build1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "7.24.6+dfsg+~cs3.2.0-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "8.5.0+dfsg+~cs3.2.0-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "8.5.0+dfsg+~cs3.2.0-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "8.9.0+dfsg+~cs3.2.0-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "node-undici",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "7.3.0+dfsg1+~cs24.12.11-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "7.16.0+dfsg+~cs3.2.0-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "7.18.2+dfsg+~cs3.2.0-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "7.18.2+dfsg+~cs3.2.0-1build1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "low",
    "structured": {
      "id": "UBUNTU-CVE-2026-18540",
      "aliases": [
        "UBUNTU-CVE-2026-18540"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "node-undici",
            "purl": "pkg:deb/ubuntu/node-undici?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "5.22.1+dfsg1+~cs20.10.10.2-1ubuntu1",
            "5.26.3+dfsg1+~cs23.10.12-2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18540.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "node-llhttp",
                "binary_version": "9.1.3~5.26.3+dfsg1+~cs23.10.12-2"
              },
              {
                "binary_name": "node-undici",
                "binary_version": "5.26.3+dfsg1+~cs23.10.12-2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "node-undici",
            "purl": "pkg:deb/ubuntu/node-undici?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "7.18.2+dfsg+~cs3.2.0-1build1",
            "7.24.6+dfsg+~cs3.2.0-3",
            "8.5.0+dfsg+~cs3.2.0-2",
            "8.5.0+dfsg+~cs3.2.0-3",
            "8.9.0+dfsg+~cs3.2.0-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18540.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "node-undici",
                "binary_version": "8.9.0+dfsg+~cs3.2.0-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "node-undici",
            "purl": "pkg:deb/ubuntu/node-undici?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "7.3.0+dfsg1+~cs24.12.11-2",
            "7.16.0+dfsg+~cs3.2.0-2",
            "7.18.2+dfsg+~cs3.2.0-1",
            "7.18.2+dfsg+~cs3.2.0-1build1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18540.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "node-undici",
                "binary_version": "7.18.2+dfsg+~cs3.2.0-1build1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:56:47.257176157Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-18540"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-18540",
        "https://www.cve.org/CVERecord?id=CVE-2026-18540",
        "https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-18540",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 356257,
  "published_at": "2026-09-04T18:17:00+00:00"
}