Is CVE-2026-40891 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40891 being exploited in the wild.

How severe is CVE-2026-40891?

Medium severity, with a CVSS score of 5.3, published 23 April 2026.

Which products and versions are affected?

OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) >= 1.13.1, < 1.15.3, ECOSYSTEM:introduced=1.13.1,fixed=1.15.3.

Is there a fix for CVE-2026-40891?

Yes. OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet): upgrade to 1.15.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Am I affected by CVE-2026-40891?

Check whether you run OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) or Opentelemetry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40891: OpenTelemetry dotnet: Unbounded `grpc-status-details-bin` parsing in OTLP/gRPC retry handling

Q: Is there a fix for CVE-2026-40891?

Yes. OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet): upgrade to 1.15.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: Am I affected by CVE-2026-40891?

Check whether you run OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) or Opentelemetry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40891 · Severity: medium · CVSS 5.3 · Published 2026-04-23

OpenTelemetry dotnet is a dotnet telemetry framework. From 1.13.1 to before 1.15.2, 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). This vulnerability is fixed in 1.15.2.

Technologies: OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet), Opentelemetry. Vendors: NuGet, Opentelemetry.

Quick answers

Is CVE-2026-40891 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40891 being exploited in the wild.
How severe is CVE-2026-40891?: Medium severity, with a CVSS score of 5.3, published 23 April 2026.
Which products and versions are affected?: OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) >= 1.13.1, < 1.15.3, ECOSYSTEM:introduced=1.13.1,fixed=1.15.3.
Is there a fix for CVE-2026-40891?: Yes. OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet): upgrade to 1.15.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-40891?: Check whether you run OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) or Opentelemetry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet): upgrade to 1.15.3 or later

dotnet add package OpenTelemetry.Exporter.OpenTelemetryProtocol --version 1.15.3

Affected products

OpenTelemetry.Exporter.OpenTelemetryProtocol (NuGet) >= 1.13.1, < 1.15.3, ECOSYSTEM:introduced=1.13.1,fixed=1.15.3
Opentelemetry

Identifiers

CVE-2026-40891
GHSA-mr8r-92fq-pj8p

References

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