{"id":"GHSA-mr8r-92fq-pj8p","revision":"87310116c4ff4e118a708111f528864c","records":[{"revision":"87310116c4ff4e118a708111f528864c","observedAt":"2026-10-23T16:01:25.029+00:00","statement":{"source":"osv","id":"GHSA-mr8r-92fq-pj8p","aliases":["CVE-2026-40891"],"title":"OpenTelemetry dotnet: Unbounded `grpc-status-details-bin` parsing in OTLP/gRPC retry handling","description":"### Summary\n\nWhen exporting telemetry over gRPC using the OpenTelemetry Protocol (OTLP), the exporter may parse a server-provided `grpc-status-details-bin` trailer during retry handling. Prior to the fix, a malformed trailer could encode an extremely large length-delimited protobuf field which was used directly for allocation, allowing excessive memory allocation and potential denial of service (DoS).\n\n### Details\n\n#5980 introduced a retry path that parses `grpc-status-details-bin` to extract gRPC retry delay information for retryable responses.\n\nOn that path:\n\n- `OtlpGrpcExportClient` captures `grpc-status-details-bin` from retryable status responses (`ResourceExhausted` / `Unavailable`).\n- `OtlpRetry` invokes `GrpcStatusDeserializer.TryGetGrpcRetryDelay` using this untrusted trailer value.\n- `GrpcStatusDeserializer.DecodeBytes` decoded a protobuf varint length and allocated `new byte[length]` without validating the bounds against the remaining payload size.\n\nA malicious or compromised collector (or a MitM in weakly-protected deployments) could return a crafted `grpc-status-details-bin` payload that forces oversized allocation and memory exhaustion in the instrumented process.\n\n### Impact\n\nIf an OTLP/gRPC endpoint is attacker-controlled (or traffic is intercepted), a crafted retryable response can trigger large allocations during trailer parsing, which may exhaust memory and cause process instability/crash (availability impact / DoS).\n\n### Mitigation\n\nThe application's configured back-end/collector endpoint needs to behave maliciously. If the collector/back-end is a well-behaved implementation response bodies should not be excessively large if a request error occurs.\n\n### Workarounds\n\nNone known.\n\n### Remediation\n\n[#7064](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7064) updates `GrpcStatusDeserializer` to validate decoded length-delimited field sizes before allocation by ensuring the requested length is sane and does not exceed the remaining payload.\n\nThis causes malformed or truncated `grpc-status-details-bin` payloads to fail safely instead of attempting unbounded allocation.","state":0,"publishedAt":"2026-04-23T21:40:29+00:00","modifiedAt":"2026-09-10T03:50:44.892821+00:00","affected":[{"ecosystem":"NuGet","name":"OpenTelemetry.Exporter.OpenTelemetryProtocol","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"1.13.1"},{"kind":"fixed","version":"1.15.3"}]}],"versions":["1.13.1","1.14.0","1.15.0","1.15.1","1.15.2"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-mr8r-92fq-pj8p","https://nvd.nist.gov/vuln/detail/CVE-2026-40891","https://github.com/open-telemetry/opentelemetry-dotnet/pull/5980","https://github.com/open-telemetry/opentelemetry-dotnet/pull/7064","https://github.com/open-telemetry/opentelemetry-dotnet"],"sourceUrl":"https://github.com/advisories/GHSA-mr8r-92fq-pj8p","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-mr8r-92fq-pj8p","identifiers":["GHSA-mr8r-92fq-pj8p","CVE-2026-40891"]},"retained":false,"historicalAffected":[]}],"coverage":[]}