GHSA-mr8r-92fq-pj8p
OpenTelemetry dotnet: Unbounded `grpc-status-details-bin` parsing in OTLP/gRPC retry handling
Quick fix
GHSA-mr8r-92fq-pj8p — OpenTelemetry.Exporter.OpenTelemetryProtocol: upgrade to the fixed version with the command below.
dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol --version 1.15.3Details
### Summary
When 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).
### Details
#5980 introduced a retry path that parses `grpc-status-details-bin` to extract gRPC retry delay information for retryable responses.
On that path:
- `OtlpGrpcExportClient` captures `grpc-status-details-bin` from retryable status responses (`ResourceExhausted` / `Unavailable`). - `OtlpRetry` invokes `GrpcStatusDeserializer.TryGetGrpcRetryDelay` using this untrusted trailer value. - `GrpcStatusDeserializer.DecodeBytes` decoded a protobuf varint length and allocated `new byte[length]` without validating the bounds against the remaining payload size.
A 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.
### Impact
If 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).
### Mitigation
The 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.
### Workarounds
None known.
### Remediation
[#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.
This causes malformed or truncated `grpc-status-details-bin` payloads to fail safely instead of attempting unbounded allocation.
Are you affected?
Enter the version of the package you're using.
Affected packages
1.13.1Fixed in: 1.15.3dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol --version 1.15.3References
- https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-mr8r-92fq-pj8p[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-40891[ADVISORY]
- https://github.com/open-telemetry/opentelemetry-dotnet/pull/5980[WEB]
- https://github.com/open-telemetry/opentelemetry-dotnet/pull/7064[WEB]
- https://github.com/open-telemetry/opentelemetry-dotnet[PACKAGE]