Uncontrolled recursion in the Ion reader in Amazon Ion Python

{
  "id": "ff436dc720009f4fa97d32bb18acdfa132a28c9d1c3fa62b58a024422101a430",
  "url": "https://osv.dev/vulnerability/CVE-2026-104020",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Uncontrolled recursion in the Ion reader in Amazon Ion Python",
    "summary": "Uncontrolled recursion in the Ion reader in Amazon Ion Python before 0.15.0 might allow a remote unauthenticated actor to crash the application using the library, resulting in a denial of service, via a crafted, deeply nested Ion value. To remediate this issue, users should upgrade to version 0.15.0 or later.",
    "evidence": "osv:CVE-2026-104020",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-104020",
      "aliases": [
        "CVE-2026-104020",
        "GHSA-93q6-f8hx-vv7f"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/amazon-ion/ion-python",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "46555409cb3fd02f8bb00dee9f8baf610155e9f6"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.15.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "46555409cb3fd02f8bb00dee9f8baf610155e9f6"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.15.0"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.15.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.14.6",
            "v0.14.5",
            "v0.14.4",
            "v0.14.3",
            "v0.14.2",
            "v0.14.1",
            "v0.14.0",
            "v0.13.0",
            "v0.12.0",
            "v0.11.3",
            "v0.11.2",
            "v0.11.1",
            "v0.10.0",
            "v0.9.3",
            "v0.9.2",
            "v0.9.1",
            "v0.9.0",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.1",
            "v0.4.0",
            "v0.3.1",
            "v0.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-104020.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.995387012Z",
      "provider": "osv",
      "references": [
        "https://aws.amazon.com/security/security-bulletins/2026-122-aws/",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104020.json",
        "https://github.com/amazon-ion/ion-python/security/advisories/GHSA-93q6-f8hx-vv7f",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-104020",
        "https://github.com/amazon-ion/ion-python/releases/tag/v0.15.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-674"
        ],
        "cna_assigner": "AMZN",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104020.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-104020",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491436,
  "published_at": "2026-10-01T20:36:33.967+00:00"
}