{"id":"GHSA-g94r-2vxg-569j","revision":"60fb08e2206d4ab097fb308410879e2c","records":[{"revision":"60fb08e2206d4ab097fb308410879e2c","observedAt":"2026-10-23T16:01:25.029+00:00","statement":{"source":"osv","id":"GHSA-g94r-2vxg-569j","aliases":["CVE-2026-40894"],"title":"OpenTelemetry dotnet: Excessive memory allocation when parsing OpenTelemetry propagation headers","description":"### Summary\n\nThe 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.\n\n### Details\n\n#### Exceeding Limits\n\n[`BaggagePropagator.Inject<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/fc1a2864d1665bda857089e11fe9247e3c75637a/src/OpenTelemetry.Api/Context/Propagation/BaggagePropagator.cs#L93-L112) does not enforce the length limit of `8192` characters if the injected baggage contains only one item.\n\nThis change was introduced by #1048.\n\n#### Excessive allocation\n\nThe following methods eagerly allocate intermediate arrays before applying size limits.\n\n- [`BaggagePropagator.Extract<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/888d1bf2489fb7408d3c5e8758a5bbffa89a8fb2/src/OpenTelemetry.Api/Context/Propagation/BaggagePropagator.cs#L52-L55) - this change was introduced by #1048.\n- [`BaggagePropagator.Inject<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/888d1bf2489fb7408d3c5e8758a5bbffa89a8fb2/src/OpenTelemetry.Api/Context/Propagation/BaggagePropagator.cs#L138-L157) - this change was introduced by #1048.\n- [`B3Propagator.Extract<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/888d1bf2489fb7408d3c5e8758a5bbffa89a8fb2/src/OpenTelemetry.Extensions.Propagators/B3Propagator.cs#L203-L207) - this change was introduced by #533.\n- [`B3Propagator.Extract<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/888d1bf2489fb7408d3c5e8758a5bbffa89a8fb2/src/OpenTelemetry.Api/Context/Propagation/B3Propagator.cs#L204-L214) - this change was introduced by #3244.\n- [`JaegerPropagator.Extract<T>()`](https://github.com/open-telemetry/opentelemetry-dotnet/blob/888d1bf2489fb7408d3c5e8758a5bbffa89a8fb2/src/OpenTelemetry.Extensions.Propagators/JaegerPropagator.cs#L150-L154) - this change was introduced by #3309.\n\n### Impact\n\nExcessively large propagation headers, particularly in degenerate/malformed cases that consist or large numbers of delimiter characters, can allocate excessive amounts of memory for intermediate storage of parsed content relative to the size of the original input.\n\n### Mitigation\n\nHTTP servers often set maximum limits on the length of HTTP request headers, such as [Internet Information Services (IIS)](https://learn.microsoft.com/iis/configuration/system.webserver/security/requestfiltering/requestlimits/headerlimits/) which sets a default limit of 16KB and [nginx](https://nginx.org/docs/http/ngx_http_core_module.html#large_client_header_buffers) which sets a default limit of 8KB.\n\n### Workarounds\n\nPossible workarounds include:\n\n- Configuring appropriate HTTP request header limits.\n- Disabling baggage and/or trace propagation.\n\n### Remediation\n\n[#7061](https://github.com/open-telemetry/opentelemetry-dotnet/pull/7061) refactors the handling of baggage, B3 and Jaeger propagation headers to stop parsing eagerly when limits are exceeded and avoid allocating intermediate arrays.","state":0,"publishedAt":"2026-04-23T21:43:53+00:00","modifiedAt":"2026-09-10T03:50:44.5800188+00:00","affected":[{"ecosystem":"NuGet","name":"OpenTelemetry.Api","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"0.5.0-beta.2"},{"kind":"fixed","version":"1.15.3"}]}],"versions":["1.0.0-rc2","1.0.0-rc3","1.0.0-rc4","1.0.1","1.1.0","1.1.0-beta1","1.1.0-beta2","1.1.0-beta3","1.1.0-beta4","1.1.0-rc1","1.10.0","1.11.0","1.11.1","1.11.2","1.12.0","1.13.0","1.13.1","1.14.0","1.15.0","1.15.1","1.15.2","1.2.0","1.2.0-rc1","1.2.0-rc2","1.2.0-rc3","1.2.0-rc4","1.2.0-rc5","1.3.0","1.3.1","1.3.2","1.4.0","1.5.0","1.5.1","1.6.0","1.7.0","1.8.0","1.8.1","1.9.0"],"rawVersionEvidence":null},{"ecosystem":"NuGet","name":"OpenTelemetry.Extensions.Propagators","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"1.3.1"},{"kind":"fixed","version":"1.15.3"}]}],"versions":["1.10.0","1.11.0","1.11.1","1.11.2","1.12.0","1.13.0","1.13.1","1.14.0","1.15.0","1.15.1","1.15.2","1.3.1","1.3.2","1.4.0","1.5.0","1.5.1","1.6.0","1.7.0","1.8.0","1.8.1","1.9.0"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-g94r-2vxg-569j","https://nvd.nist.gov/vuln/detail/CVE-2026-40894","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/3533","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","https://github.com/open-telemetry/opentelemetry-dotnet/releases/tag/core-1.15.3"],"sourceUrl":"https://github.com/advisories/GHSA-g94r-2vxg-569j","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-g94r-2vxg-569j","identifiers":["GHSA-g94r-2vxg-569j","CVE-2026-40894"]},"retained":false,"historicalAffected":[]}],"coverage":[]}