What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-23 · updated 2026-10-26
• Weakness: CWE-789

Description

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.

Affected products

• open-telemetry opentelemetry-go: from 0.5.0 before 1.15.3 — fixed in 1.15.3
• open-telemetry OpenTelemetry.Api: from 0.5.0 before 1.15.3 — fixed in 1.15.3
• open-telemetry OpenTelemetry.Extensions.Propagators: from 1.3.0 (excl.) before 1.15.3 — fixed in 1.15.3

How to fix

Upgrade to a fixed version: open-telemetry opentelemetry-go 1.15.3; open-telemetry OpenTelemetry.Api 1.15.3; open-telemetry OpenTelemetry.Extensions.Propagators 1.15.3. Check the vendor advisory for mitigations.

References

• https://github.com/open-telemetry/opentelemetry-dotnet/pull/1048
• https://github.com/open-telemetry/opentelemetry-dotnet/pull/3244
• https://github.com/open-telemetry/opentelemetry-dotnet/pull/3309
• https://github.com/open-telemetry/opentelemetry-dotnet/pull/533
• https://github.com/open-telemetry/opentelemetry-dotnet/pull/7061
• https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-g94r-2vxg-569j

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