{"affected":[{"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-q834-8qmm-v933/GHSA-q834-8qmm-v933.json"},"package":{"ecosystem":"NuGet","name":"OpenTelemetry.Exporter.OpenTelemetryProtocol","purl":"pkg:nuget/OpenTelemetry.Exporter.OpenTelemetryProtocol"},"ranges":[{"events":[{"introduced":"1.13.1"},{"fixed":"1.15.2"}],"type":"ECOSYSTEM"}],"versions":["1.13.1","1.14.0","1.15.0","1.15.1"]}],"aliases":["CVE-2026-40182"],"database_specific":{"cwe_ids":["CWE-789"],"github_reviewed":true,"github_reviewed_at":"2026-04-23T21:26:10Z","nvd_published_at":"2026-04-23T18:16:28Z","severity":"MODERATE"},"details":"### Summary\n\nWhen exporting telemetry to a back-end/collector over gRPC or HTTP using OpenTelemetry Protocol format (OTLP), if the request results in a unsuccessful request (i.e. HTTP 4xx or 5xx), the response is read into memory with no upper-bound on the number of bytes consumed.\n\nThis could cause memory exhaustion in the consuming application if the configured back-end/collector endpoint is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response.\n\n### Details\n\nhttps://github.com/open-telemetry/opentelemetry-dotnet/pull/6564 introduced a change to read the response body when a non-200 HTTP status code is received when exporting telemetry to aid debugging by operators so that the error response is included in the logs emitted by the exporter for both [gRPC](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpGrpcExportClient.cs#L123-L134) and [HTTP/protobuf](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpHttpExportClient.cs#L36-L41).\n\nAn unintended consequence of this change is that the response body is [fully read into memory when received with no upper-bound](https://github.com/open-telemetry/opentelemetry-dotnet/blob/640cf63628567b76b348b26988920dbc0b5c1662/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpExportClient.cs#L68-L89).\n\nThis vulnerability was surfaced during the investigation of GHSA-w8rr-5gcm-pp58.\n\n### Impact\n\nIf an application using the OTLP exporter is configured to use a back-end/collector endpoint that is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned by the response the application could have its memory exhausted and create a denial-of-service condition.\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[#7017](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7017) updates the OTLP exporter for both gRPC and HTTP to:\n\n- Limit the number of bytes read from the response body in an error condition to 4MiB (see https://github.com/open-telemetry/opentelemetry-proto/pull/781);\n- Only attempt to read the response body if OpenTelemetry error logging is enabled.","id":"GHSA-q834-8qmm-v933","modified":"2026-09-10T03:51:02.815079557Z","published":"2026-04-23T21:26:10Z","references":[{"type":"WEB","url":"https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-q834-8qmm-v933"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40182"},{"type":"WEB","url":"https://github.com/open-telemetry/opentelemetry-dotnet/pull/6564"},{"type":"WEB","url":"https://github.com/open-telemetry/opentelemetry-dotnet/pull/7017"},{"type":"WEB","url":"https://github.com/open-telemetry/opentelemetry-proto/pull/781"},{"type":"PACKAGE","url":"https://github.com/open-telemetry/opentelemetry-dotnet"}],"schema_version":"1.9.0","severity":[{"score":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","type":"CVSS_V3"}],"summary":"OpenTelemetry dotnet: OTLP exporter reads unbounded HTTP response bodies"}