eventsource-encoder: SSE event injection via unsanitized event and id fields

{
  "id": "f3a0b9a76be1e5fbfea801494d3a3754107d96ff32de40074ced3734e930c52c",
  "url": "https://osv.dev/vulnerability/CVE-2026-44214",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "eventsource-encoder: SSE event injection via unsanitized event and id fields",
    "summary": "eventsource-encoder encodes events as well-formed EventSource/Server Sent Event (SSE) messages. Prior to 1.0.2, eventsource-encoder does not sanitize the event or id fields of an EventSourceMessage before serializing them. An attacker who controls either field can inject arbitrary Server-Sent Events line terminators (\\n, \\r, or \\r\\n) and thereby forge additional SSE fields or entire messages on the stream. This vulnerability is fixed in 1.0.2.",
    "evidence": "osv:CVE-2026-44214",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-44214",
      "aliases": [
        "CVE-2026-44214",
        "GHSA-m9g3-3g99-mhpx"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rexxars/eventsource-encoder",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0e24a55b577c43dd7048cb4ced63833b558b6a41"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.0.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:rexxars:eventsource-encoder:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.0.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.0.1",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-44214.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.452089677Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44214.json",
        "https://github.com/rexxars/eventsource-encoder/security/advisories/GHSA-m9g3-3g99-mhpx",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-44214"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-113",
          "CWE-93"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44214.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-44214",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491034,
  "published_at": "2026-05-26T19:34:32.273+00:00"
}