CVE-2026-40894: OpenTelemetry dotnet: Excessive memory allocation when parsing OpenTelemetry propagation headers

CVE-2026-40894 · Severity: medium · CVSS 5.3 · Published 2026-04-23

OpenTelemetry dotnet is a dotnet telemetry framework. In OpenTelemetry.Api 0.5.0-beta.2 to 1.15.2 and OpenTelemetry.Extensions.Propagators 1.3.1 to 1.15.2, The implementation details of the baggage, B3 and Jaeger processing code in the OpenTelemetry.Api and OpenTelemetry.Extensions.Propagators NuGet packages can allocate excessive memory when parsing which could create a potential denial of service (DoS) in the consuming application. This vulnerability is fixed in 1.15.3.

Technologies: Opentelemetry, Opentelemetry-Api. Vendors: NuGet, Opentelemetry.

Quick answers

Is CVE-2026-40894 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-40894 being exploited in the wild.
How severe is CVE-2026-40894?
Medium severity, with a CVSS score of 5.3, published 23 April 2026.
Which products and versions are affected?
OpenTelemetry.Api (NuGet) >= 0.5.0-beta.2, < 1.15.3, ECOSYSTEM:introduced=0.5.0-beta.2,fixed=1.15.3; OpenTelemetry.Extensions.Propagators (NuGet) >= 1.3.1, < 1.15.3, ECOSYSTEM:introduced=1.3.1,fixed=1.15.3.
Is there a fix for CVE-2026-40894?
Yes. OpenTelemetry.Api (NuGet): upgrade to 1.15.3 or later; OpenTelemetry.Extensions.Propagators (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-2026-40894?
Check whether you run OpenTelemetry.Api (NuGet), OpenTelemetry.Extensions.Propagators (NuGet), Opentelemetry or one of the others listed 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.Api (NuGet): upgrade to 1.15.3 or later
    dotnet add package OpenTelemetry.Api --version 1.15.3
  • OpenTelemetry.Extensions.Propagators (NuGet): upgrade to 1.15.3 or later
    dotnet add package OpenTelemetry.Extensions.Propagators --version 1.15.3

Affected products

  • OpenTelemetry.Api (NuGet) >= 0.5.0-beta.2, < 1.15.3, ECOSYSTEM:introduced=0.5.0-beta.2,fixed=1.15.3
  • OpenTelemetry.Extensions.Propagators (NuGet) >= 1.3.1, < 1.15.3, ECOSYSTEM:introduced=1.3.1,fixed=1.15.3
  • Opentelemetry
  • Opentelemetry-Api
  • Opentelemetry.Extensions.Propagators

Identifiers

  • CVE-2026-40894
  • GHSA-g94r-2vxg-569j

References

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