Unbounded HTTP response body read in OpenTelemetry.Sampler.AWS

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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.

Source published

23 Apr 2026 18:22:31 UTC

Source modified

23 Apr 2026 19:16:04 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Source published

Apr 23, 2026, 6:22:31 PM (timezone not stated)

Source modified

Apr 23, 2026, 7:16:04 PM (timezone not stated)

Observed here

28 Oct 2026 05:06:59 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Source published

23 Apr 2026 19:17:29 UTC

Source modified

26 Oct 2026 21:10:00 UTC

Observed here

27 Oct 2026 10:10:07 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

### Summary `OpenTelemetry.Sampler.AWS` reads unbounded HTTP response bodies from a configured AWS X-Ray remote sampling endpoint into memory. `OpenTelemetry.Resources.AWS` reads unbounded HTTP response bodies from a configured AWS EC2/ECS/EKS remote instance metadata service endpoint into memory. Both of these would allow an attacker-controlled endpoint or be acting as a Man-in-the-Middle (MitM) to cause excessive memory allocation and possible process termination (via Out of Memory (OOM)). ### Details #### OpenTelemetry.Sampler.AWS `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. #### OpenTelemetry.Resources.AWS The [`AWSEC2Detector`](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/171c6b81f88831641b56b470e6f92862e605013d/src/OpenTelemetry.Resources.AWS/AWSEC2Detector.cs), [`AWSECSDetector`](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/171c6b81f88831641b56b470e6f92862e605013d/src/OpenTelemetry.Resources.AWS/AWSECSDetector.cs) and [`AWSEKSDetector`](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/blob/171c6b81f88831641b56b470e6f92862e605013d/src/OpenTelemetry.Resources.AWS/AWSEKSDetector.cs) classes all make HTTP requests to the relevant AWS metadata service (`http://169.254.169.254`, `ECS_CONTAINER_METADATA_URI`/`ECS_CONTAINER_METADATA_URI_V4` or `https://kubernetes.default.svc` respectively) to obtain metadata about the running process and its infrastructure. An attacker who controls the configured endpoint(s), or who can intercept traffic to them (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. ### Impact Denial of Service (DoS). An attacker can destabilize or crash the application by forcing unbounded memory allocation through the X-Ray sampling and/or EC2/ECS/EKS HTTP response paths. ### Mitigating Factors - The default X-Ray sampling endpoint is `http://localhost:2000`, which limits remote exposure in default configurations. - Risk increases materially when operators configure the sampler to point at a remote or untrusted endpoint. ### Patches Fixed in `OpenTelemetry.Sampler.AWS` version `0.1.0-alpha.8` and `OpenTelemetry.Resources.AWS` version `1.15.1`. The fixes (#4100, #4122) introduce changes that introduce limits to `HttpClient` requests so that the response body is streamed rather than buffered entirely in memory. ### Workarounds - Ensure the X-Ray sampling endpoint (`http://localhost:2000` by default) is not accessible to untrusted parties. - Use network-level controls (firewall rules, mTLS, service mesh) to prevent Man-in-the-Middle (MitM) attacks on the sampling endpoint and/or EC2/ECS/EKS connection. - If using a remote endpoint, place it behind a reverse proxy that enforces a response body size limit.

Source published

23 Apr 2026 21:44:31 UTC

Source modified

23 Apr 2026 22:11:25 UTC

Observed here

23 Oct 2026 16:01:25 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · MODERATE