Vyper 0.3.8 through 0.5.0b1 Memory Misread via Ternary Nested Array Selection

{
  "id": "5bc5b7024f432e0db50515d16f09051d1911db1a50948335c8fae342428abb2c",
  "url": "https://osv.dev/vulnerability/CVE-2026-114115",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Vyper 0.3.8 through 0.5.0b1 Memory Misread via Ternary Nested Array Selection",
    "summary": "Vyper 0.3.8 through 0.5.0b1 contains a compiler miscompilation vulnerability in parse_IfExp that reads nested arrays with narrower inner bounds using the wider result type's memory layout. When a ternary selects the narrower array, inner arrays after the first are read at wrong offsets, causing contracts to silently store corrupted values or revert.",
    "evidence": "osv:CVE-2026-114115",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-114115",
      "aliases": [
        "CVE-2026-114115",
        "GHSA-cw3h-xwxq-8cx2"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/vyperlang/vyper",
              "type": "GIT",
              "events": [
                {
                  "introduced": "036f153683e0d55b890305eb4c77680a0872fcba"
                },
                {
                  "fixed": "1fb7dfe2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.3.8"
                      },
                      {
                        "last_affected": "0.5.0b1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "1fb7dfe2"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-114115.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:53.167402615Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/114xxx/CVE-2026-114115.json",
        "https://github.com/vyperlang/vyper/security/advisories/GHSA-cw3h-xwxq-8cx2",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-114115",
        "https://www.vulncheck.com/advisories/vyper-0.3.8-through-0.5-0b1-memory-misread-via-ternary-nested-array-selection",
        "https://github.com/vyperlang/vyper/commit/1fb7dfe2"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-843"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/114xxx/CVE-2026-114115.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114115",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 522260,
  "published_at": "2026-10-21T00:37:13.251+00:00"
}