{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.40.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "go.opentelemetry.io/otel/baggage"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.36.0"
            },
            {
              "fixed": "1.41.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.40.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "go.opentelemetry.io/otel/propagation"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.36.0"
            },
            {
              "fixed": "1.41.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-29181"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-07T20:12:57Z",
    "nvd_published_at": "2026-04-07T21:17:16Z",
    "severity": "HIGH"
  },
  "details": "multi-value `baggage:` header extraction parses each header field-value independently and aggregates members across values. this allows an attacker to amplify cpu and allocations by sending many `baggage:` header lines, even when each individual value is within the 8192-byte per-value parse limit.\n\n## severity\n\nHIGH (availability / remote request amplification)\n\n## relevant links\n\n- repository: https://github.com/open-telemetry/opentelemetry-go\n- pinned callsite: https://github.com/open-telemetry/opentelemetry-go/blob/1ee4a4126dbdd1bc79e9fae072fa488beffac52a/propagation/baggage.go#L58\n\n## vulnerability details\n\n**pins:** open-telemetry/opentelemetry-go@1ee4a4126dbdd1bc79e9fae072fa488beffac52a\n**as-of:** 2026-02-04\n**policy:** direct (no program scope provided)\n\n**callsite:** propagation/baggage.go:58 (`extractMultiBaggage`)\n**attacker control:** inbound HTTP request headers (many `baggage` field-values) \u2192 `propagation.HeaderCarrier.Values(\"baggage\")` \u2192 repeated `baggage.Parse` + member aggregation\n\n### root cause\n\n`extractMultiBaggage` iterates over all `baggage` header field-values and parses each one independently, then appends members into a shared slice. the 8192-byte parsing cap applies per header value, but the multi-value path repeats that work once per header line (bounded only by the server/proxy header byte limit).\n\n### impact\n\nin a default `net/http` configuration (max header bytes 1mb), a single request with many `baggage:` header field-values can cause large per-request allocations and increased latency.\n\nexample from the attached PoC harness (darwin/arm64; 80 values; 40 requests):\n\n- canonical: `per_req_alloc_bytes=10315458` and `p95_ms=7`\n- control: `per_req_alloc_bytes=133429` and `p95_ms=0`\n\n## proof of concept\n\ncanonical:\n\n```bash\nmkdir -p poc\nunzip poc.zip -d poc\ncd poc\nmake test\n```\n\noutput (excerpt):\n\n```\n[CALLSITE_HIT]: propagation/baggage.go:58 extractMultiBaggage\n[PROOF_MARKER]: baggage_multi_value_amplification p95_ms=7 per_req_alloc_bytes=10315458 per_req_allocs=16165\n```\n\ncontrol:\n\n```bash\ncd poc\nmake control\n```\n\ncontrol output (excerpt):\n\n```\n[NC_MARKER]: baggage_single_value_baseline p95_ms=0 per_req_alloc_bytes=133429 per_req_allocs=480\n```\n\n**expected:** multiple `baggage` header field-values should be semantically equivalent to a single comma-joined `baggage` value and should not multiply parsing/alloc work within the effective header byte budget.\n**actual:** multiple `baggage` header field-values trigger repeated parsing and member aggregation, causing high per-request allocations and increased latency even when each individual value is within 8192 bytes.\n\n## fix recommendation\n\navoid repeated parsing across multi-values by enforcing a global budget and/or normalizing multi-values into a single value before parsing. one mitigation approach is to treat multi-values as a single comma-joined string and cap total parsed bytes (for example 8192 bytes total).\n\n**fix accepted when:** under the default PoC harness settings, canonical stays within 2x of control for `per_req_alloc_bytes` and `per_req_allocs`, and `p95_ms` stays below 2ms.\n\n\n[poc.zip](https://github.com/user-attachments/files/25079945/poc.zip)\n[PR_DESCRIPTION.md](https://github.com/user-attachments/files/25079946/PR_DESCRIPTION.md)",
  "id": "GHSA-mh2q-q3fh-2475",
  "modified": "2026-04-07T22:16:39Z",
  "published": "2026-04-07T20:12:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-mh2q-q3fh-2475"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-29181"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/pull/7880"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/commit/aa1894e09e3fe66860c7885cb40f98901b35277f"
    },
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      "type": "PACKAGE",
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    {
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  "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:H",
      "type": "CVSS_V3"
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  ],
  "summary": "OpenTelemetry-Go: multi-value `baggage` header extraction causes excessive allocations (remote dos amplification)"
}

{
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        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
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          "text": "GitHub_M",
          "title": "Assigning CNA"
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      ],
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        {
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          "date": "2026-04-11T01:03:43.000Z",
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        {
          "category": "none_available",
          "date": "2026-04-11T01:03:43.000Z",
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        {
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        {
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          "date": "2026-04-11T01:03:43.000Z",
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        {
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          "date": "2026-04-11T01:03:43.000Z",
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          ]
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            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "products": [
            "17084-4",
            "17084-11",
            "17084-10",
            "17084-9",
            "17084-3",
            "17084-8",
            "17086-2",
            "17084-1",
            "17084-7",
            "17084-6",
            "17084-5"
          ]
        }
      ],
      "title": "OpenTelemetry-Go multi-value `baggage` header extraction causes excessive allocations (remote dos amplification)"
    }
  ]
}