{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "OpenTelemetry.Api"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.5.0-beta.2"
            },
            {
              "fixed": "1.15.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "OpenTelemetry.Extensions.Propagators"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.3.1"
            },
            {
              "fixed": "1.15.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40894"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-789"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-23T21:43:53Z",
    "nvd_published_at": "2026-04-23T19:17:28Z",
    "severity": "MODERATE"
  },
  "details": "### 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\u003cT\u003e()`](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\u003cT\u003e()`](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\u003cT\u003e()`](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\u003cT\u003e()`](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\u003cT\u003e()`](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\u003cT\u003e()`](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.",
  "id": "GHSA-g94r-2vxg-569j",
  "modified": "2026-04-23T21:43:54Z",
  "published": "2026-04-23T21:43:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/security/advisories/GHSA-g94r-2vxg-569j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40894"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/1048"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/3244"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/3309"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/3533"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/533"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/pull/7061"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-dotnet/releases/tag/core-1.15.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OpenTelemetry dotnet: Excessive memory allocation when parsing OpenTelemetry propagation headers"
}