OpenTelemetry.Exporter.OpenTelemetryProtocol: Disk retry default temp path enables local blob injection for OTLP Exporter

{
  "id": "9757ef9aa52846edbeab3aae764830863ad473ffa050f592f105c8fd692d5266",
  "url": "https://osv.dev/vulnerability/CVE-2026-42191",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "OpenTelemetry.Exporter.OpenTelemetryProtocol: Disk retry default temp path enables local blob injection for OTLP Exporter",
    "summary": "OpenTelemetry.Exporter.OpenTelemetryProtocol is the OTLP (OpenTelemetry Protocol) exporter implementation. From 1.8.0 to 1.15.2, the OTLP disk retry feature in OpenTelemetry.Exporter.OpenTelemetryProtocol silently fell back to Path.GetTempPath() when OTEL_DOTNET_EXPERIMENTAL_OTLP_RETRY=disk was set but OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_DIRECTORY_PATH was not configured. The exporter stored and loaded *.blob files under fixed, signal-named subdirectories (traces, metrics, logs) beneath that shared temporary root path. On multi-user systems where the temporary directory is accessible to other local accounts, this allows an attacker to write crafted *.blob files, read *.blob files written by the application between export failures, or deposit numerous or oversized blob files, degrading retry-loop performance or consuming disk space. This vulnerability is fixed in 1.15.3.",
    "evidence": "osv:CVE-2026-42191",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-42191",
      "aliases": [
        "CVE-2026-42191",
        "GHSA-4625-4j76-fww9"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/open-telemetry/opentelemetry-dotnet",
              "type": "GIT",
              "events": [
                {
                  "introduced": "fb74013d644d56f44ef89dd57358947bd9f68345"
                },
                {
                  "fixed": "d622e6c7c899527638b53a6b06919859f5752add"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.8.0"
                      },
                      {
                        "fixed": "1.15.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:opentelemetry:opentelemetry.exporter.opentelemetryprotocol:*:*:*:*:*:.net:*:*",
                    "range": [
                      {
                        "introduced": "1.8.0"
                      },
                      {
                        "fixed": "1.15.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "coreunstable-1.15.2-beta.1",
            "core-1.15.2",
            "coreunstable-1.15.1-beta.1",
            "core-1.15.1",
            "coreunstable-1.15.0-beta.1",
            "core-1.15.0",
            "coreunstable-1.14.0-beta.1",
            "core-1.14.0",
            "core-1.14.0-rc.1",
            "coreunstable-1.13.1-beta.1",
            "core-1.13.1",
            "coreunstable-1.13.0-beta.1",
            "core-1.13.0",
            "coreunstable-1.12.0-beta.1",
            "core-1.12.0",
            "coreunstable-1.11.2-beta.1",
            "core-1.11.2",
            "core-1.11.1",
            "coreunstable-1.11.0-beta.1",
            "core-1.11.0",
            "core-1.11.0-rc.1",
            "coreunstable-1.10.0-beta.1",
            "core-1.10.0",
            "core-1.10.0-rc.1",
            "core-1.10.0-beta.1",
            "coreunstable-1.9.0-beta.2",
            "coreunstable-1.9.0-beta.1",
            "core-1.9.0",
            "core-1.9.0-rc.1",
            "coreunstable-1.9.0-alpha.2",
            "coreunstable-1.9.0-alpha.1",
            "core-1.9.0-alpha.1",
            "core-1.8.0",
            "Instrumentation.Http-1.8.1",
            "Instrumentation.AspNetCore-1.8.1",
            "Instrumentation.SqlClient-1.8.0-beta.1",
            "Instrumentation.Http-1.8.0",
            "Instrumentation.GrpcNetClient-1.8.0-beta.1",
            "Instrumentation.AspNetCore-1.8.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42191.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.500457472Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42191.json",
        "https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-4625-4j76-fww9",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42191",
        "https://github.com/open-telemetry/opentelemetry-dotnet/pull/7106"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-379"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42191.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42191",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517958,
  "published_at": "2026-05-12T19:12:03.221+00:00"
}