undici vulnerable to Denial of Service via unbounded memory in the EventSource parser

{
  "id": "4ab6fa8727101717a7473aed03764977d6a1ccc95e39dbf2b2e6e08383b72a82",
  "url": "https://osv.dev/vulnerability/GHSA-4qv8-2p9j-2685",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "undici vulnerable to Denial of Service via unbounded memory in the EventSource parser",
    "summary": "### Impact undici's `EventSource` client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed `data:` fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state. The byte-based `maxEventSize` and `maxResponseSize` limits do not bound that retained state, and `maxResponseSize` is enforced on the compressed body before decompression, so a small compressed response can expand into enough retained memory to terminate the process. The application only needs to maintain an `EventSource` connection to an untrusted peer, which controls only the response. Availability is the only impact. ### Patches Upgrade to `6.29.1`, `7.30.1`, or `8.12.2`, which bound the retained EventSource parser state (the number of `data` fields and buffered chunks, the unfinished-line length, and per-field byte totals) independently of the byte limits. ### Workarounds None.",
    "evidence": "osv:GHSA-4qv8-2p9j-2685",
    "products": [
      {
        "name": {
          "value": "undici",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.29.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "undici",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.30.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "undici",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.12.2",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "GHSA-4qv8-2p9j-2685",
      "aliases": [
        "CVE-2026-109924",
        "GHSA-4qv8-2p9j-2685"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "6.5.0"
                },
                {
                  "fixed": "6.29.1"
                }
              ]
            }
          ],
          "package": {
            "name": "undici",
            "purl": "pkg:npm/undici",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "7.0.0"
                },
                {
                  "fixed": "7.30.1"
                }
              ]
            }
          ],
          "package": {
            "name": "undici",
            "purl": "pkg:npm/undici",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"
          }
        },
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "8.0.0"
                },
                {
                  "fixed": "8.12.2"
                }
              ]
            }
          ],
          "package": {
            "name": "undici",
            "purl": "pkg:npm/undici",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-4qv8-2p9j-2685/GHSA-4qv8-2p9j-2685.json"
          }
        }
      ],
      "modified": "2026-10-23T22:30:04.104974737Z",
      "provider": "osv",
      "references": [
        "https://github.com/nodejs/undici/security/advisories/GHSA-4qv8-2p9j-2685",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-109924",
        "https://github.com/nodejs/undici/commit/299162740d5f39120092277e70efacb4d151c1c6",
        "https://github.com/nodejs/undici/commit/789ef26461c648480433846607154f52d74ec9ab",
        "https://github.com/nodejs/undici/commit/c43b23fdc6b37e1283d4347408bb16800f867d9e",
        "https://cna.openjsf.org/security-advisories.html",
        "https://github.com/nodejs/undici",
        "https://github.com/nodejs/undici/releases/tag/v6.29.1",
        "https://github.com/nodejs/undici/releases/tag/v7.30.1",
        "https://github.com/nodejs/undici/releases/tag/v8.12.2"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "severity": "MODERATE",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-15T19:17:22Z",
        "github_reviewed_at": "2026-10-23T22:13:29Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-109924",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 427062,
  "published_at": "2026-10-23T22:13:29+00:00"
}