| CVE-2026-41173 | Med | 0.38 | 5.9 | 0.00 | | Apr 23, 2026 | The AWS X-Ray Remote Sampler package provides a sampler which can get sampling configurations from AWS X-Ray. Prior to 0.1.0-alpha.8, OpenTelemetry.Sampler.AWS reads unbounded HTTP response bodies from a configured AWS X-Ray remote sampling endpoint into memory. AWSXRaySamplerClient.DoRequestAsync called HttpClient.SendAsync followed by ReadAsStringAsync(), which materializes the entire HTTP response body into a single in-memory string with no size limit. The sampling endpoint is configurable via AWSXRayRemoteSamplerBuilder.SetEndpoint (default: http://localhost:2000). An attacker who controls the configured endpoint, or who can intercept traffic to it (MitM), can return an arbitrarily large response body. This causes unbounded heap allocation in the consuming process, leading to high transient memory pressure, garbage-collection stalls, or an OutOfMemoryException that terminates the process. This vulnerability is fixed in 0.1.0-alpha.8. |
| CVE-2026-42348 | Med | 0.31 | 5.9 | 0.00 | | May 12, 2026 | OpenTelemetry.OpAmp.Client is the OpAMP client for OpenTelemetry .NET. Prior to 0.2.0-alpha.1, when receiving responses from the OpAMP server over HTTP, the OpAMP client allocates an unbounded buffer to read all bytes from the server, with no upper-bound on the number of bytes consumed. This could cause memory exhaustion in the consuming application if the configured OpAMP server is attacker-controlled (or a network attacker can MitM the connection) and an extremely large body is returned in the response. This vulnerability is fixed in 0.2.0-alpha.1. |
| CVE-2026-41483 | Med | 0.31 | 5.9 | 0.00 | | May 6, 2026 | OpenTelemetry.Resources.Azure is the .NET resource detector for Azure environments. In versions 1.15.0-beta.1 and earlier, the AzureVmMetaDataRequestor class makes HTTP requests to the Azure VM instance metadata service and reads the response body into memory without any size limit. An attacker who controls the configured endpoint, or who can intercept traffic to it via a man-in-the-middle attack, can return an arbitrarily large response body. This causes unbounded heap allocation in the consuming process, leading to high transient memory pressure, garbage-collection stalls, or an OutOfMemoryException that terminates the process. As a workaround, disable the Azure VM resource detector or use network-level controls such as firewall rules, mTLS, or a service mesh to prevent man-in-the-middle attacks on the Azure VM instance metadata endpoint. This issue is fixed in version 1.15.1-beta.1, which streams responses rather than buffering them entirely in memory and ignores responses larger than 4 MiB. |
| CVE-2026-41484 | Med | 0.27 | 5.3 | 0.00 | | May 6, 2026 | OpenTelemetry.Exporter.OneCollector is a .NET exporter that sends telemetry to a OneCollector back-end over HTTP. In versions 1.15.0 and earlier, when a request to the configured back-end or collector results in an unsuccessful HTTP 4xx or 5xx response, the HttpJsonPostTransport class reads the entire response body into memory with no upper bound on the number of bytes consumed in order to include the error response in operator logs.
An attacker who controls the configured endpoint, or who can intercept traffic to it via a man-in-the-middle attack, can return an arbitrarily large response body. This causes unbounded heap allocation in the consuming process, leading to high transient memory pressure, garbage-collection stalls, or an OutOfMemoryException that terminates the process. As a workaround, use network-level controls such as firewall rules, mTLS, or a service mesh to prevent man-in-the-middle attacks on the configured back-end or collector endpoint. This issue is fixed in version 1.15.1, which limits the number of bytes read from the response body in an error condition to 4 MiB. |
| CVE-2026-44213 | med | 0.26 | — | — | | May 8, 2026 | ### Summary
The `OpenTelemetry.Exporter.Instana` NuGet package does not validate HTTPS/TLS certificates are valid when sending telemetry to a configured Instana back-end when a proxy is configured using the `INSTANA_ENDPOINT_PROXY` environment variable.
If a network attacker can Man-in-the-Middle (MitM) the proxy connection, all OpenTelemetry telemetry data and the Instana API key are exposed to the attacker.
### Details
The [`Transport.ConfigureBackendClient()`](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/b53b6a74fde21a4cee344e584b51a0fe5bf1f337/src/OpenTelemetry.Exporter.Instana/Implementation/Transport.cs#L132-L158) method creates an `HttpClient` instance that completely disables TLS server certificate validation if the `INSTANA_ENDPOINT_PROXY` is configured with a valid proxy URL with no ability to re-enable it.
### Impact
If the configured proxy is attacker-controlled (or a network attacker MitM the connection), or if it is possible for the process' configuration to be changed to add an attacker-provided value for `INSTANA_ENDPOINT_PROXY` then all Instana telemetry could be read by an unauthorized party and the service's Instana API key compromised, potentially before being forwarded to Instana presenting no noticeable loss of telemetry data without a valid TLS server certificate being presented to the client that matches the expected hostname or IP address.
### Mitigation
The proxy configured by the `INSTANA_ENDPOINT_PROXY` environment variable must be malicious or be possible to be subject to a MitM attack.
### Workarounds
Do not configure the `INSTANA_ENDPOINT_PROXY` environment variable.
### Remediation
[#4153](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4153) refactors `HttpClient` creation so that TLS certificate validation is no longer disabled by default when using a proxy.
In environments where this capability is required, for example for local development, the previous behaviour can be restored using the `` option:
```csharp
builder.AddInstanaExporter((options) =>
{
options.HttpClientFactory = () =>
{
var handler = new HttpClientHandler()
{
#if NET
ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator,
#else
ServerCertificateCustomValidationCallback = static (_, _, _, _) => true,
#endif
};
return new HttpClient(handler, disposeHandler: true);
};
});
```
### Resources
- [PR #4153](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/4153) |
