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GHSA-HJF4-FPHR-2H65

Vulnerability from github – Published: 2026-09-29 17:59 – Updated: 2026-09-29 17:59

Summary

OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full

Details

Summary

A BatchingProcessor in go.opentelemetry.io/otel/sdk/log can enter a tight CPU loop when the asynchronous export buffer is full. Under exporter backpressure, attacker-driven high-volume log emission can keep the queue at or above the batch size, causing repeated immediate export retries and a denial of service through CPU exhaustion.

Introduced in commit: 4af9c20

Details

NewBatchingProcessor wraps the exporter with newBufferExporter(exporter, 1) (sdk/log/batch.go:116-122), so the asynchronous export input can fill quickly when the downstream exporter blocks. The poll goroutine dequeues a batch with b.q.TryDequeue, calls b.exporter.EnqueueExport(r), and then immediately sends on b.pollTrigger whenever qLen >= b.batchSize (sdk/log/batch.go:129-165).

bufferExporter.EnqueueExport is non-blocking: it sends to e.input if possible and returns false in the default case when the channel is full (sdk/log/exporter.go:221-248). TryDequeue leaves q.len unchanged when the write callback returns false (sdk/log/batch.go:289-314). Therefore, while the exporter is backpressured, EnqueueExport fails, the queue remains at or above one full batch, and the poll loop continuously retriggers itself without waiting for the ticker.

PoC

validation-artifact.zip

The validation artifact contains a PoC bundle:

validation-artifact.tar:main.go: PoC source.
validation-artifact.tar:README.md: build/run notes.
validation-artifact.tar:build_failed.log: captured build failure from the validation environment.

The PoC configures a blocking exporter and a BatchingProcessor with WithExportMaxBatchSize(1), WithExportInterval(5*time.Second), and WithMaxQueueSize(2048). It emits 1000 records, records a CPU profile for 750 ms while the exporter is blocked, then writes /workspace/validation_artifacts/busyloop.pprof.

Reproduction steps from an affected checkout at commit 4af9c20:

cd /workspace/opentelemetry-go
git checkout 4af9c20

mkdir -p validation_poc/busyloop /workspace/validation_artifacts /tmp/batchingprocessor-busyloop-poc
tar -xf /path/to/this/finding/validation-artifact.tar -C /tmp/batchingprocessor-busyloop-poc
cp /tmp/batchingprocessor-busyloop-poc/main.go validation_poc/busyloop/main.go

go build -o validation_poc/busyloop/busyloop ./validation_poc/busyloop
./validation_poc/busyloop/busyloop
go tool pprof -top /workspace/validation_artifacts/busyloop.pprof

Expected program output:

cpu profile written to /workspace/validation_artifacts/busyloop.pprof

Expected profile evidence: hot functions should include (*BatchingProcessor).poll, (*queue).TryDequeue, and (*bufferExporter).EnqueueExport, showing repeated export attempts while the exporter is blocked.

Impact

This is an availability vulnerability: uncontrolled CPU consumption caused by a busy-spin retry loop. Applications using sdk/log BatchingProcessor are impacted when an attacker can cause sustained log emission and the configured exporter or downstream collector is slow, blocked, or otherwise backpressured. The impact is limited to the embedding process but can degrade or deny service for that application.

Severity

6.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "go.opentelemetry.io/otel/sdk/log"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.21.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-81872"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-834"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-29T17:59:53Z",
    "nvd_published_at": "2026-09-16T21:17:22Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nA `BatchingProcessor` in `go.opentelemetry.io/otel/sdk/log` can enter a tight CPU loop when the asynchronous export buffer is full. Under exporter backpressure, attacker-driven high-volume log emission can keep the queue at or above the batch size, causing repeated immediate export retries and a denial of service through CPU exhaustion.\n\nIntroduced in commit: 4af9c20\n\n### Details\n\n`NewBatchingProcessor` wraps the exporter with `newBufferExporter(exporter, 1)` (`sdk/log/batch.go:116-122`), so the asynchronous export input can fill quickly when the downstream exporter blocks. The poll goroutine dequeues a batch with `b.q.TryDequeue`, calls `b.exporter.EnqueueExport(r)`, and then immediately sends on `b.pollTrigger` whenever `qLen \u003e= b.batchSize` (`sdk/log/batch.go:129-165`).\n\n`bufferExporter.EnqueueExport` is non-blocking: it sends to `e.input` if possible and returns `false` in the `default` case when the channel is full (`sdk/log/exporter.go:221-248`). `TryDequeue` leaves `q.len` unchanged when the write callback returns `false` (`sdk/log/batch.go:289-314`). Therefore, while the exporter is backpressured, `EnqueueExport` fails, the queue remains at or above one full batch, and the poll loop continuously retriggers itself without waiting for the ticker.\n\n### PoC\n\n[validation-artifact.zip](https://github.com/user-attachments/files/27494002/validation-artifact.zip)\n\nThe validation artifact contains a PoC bundle:\n\n- `validation-artifact.tar:main.go`: PoC source.\n- `validation-artifact.tar:README.md`: build/run notes.\n- `validation-artifact.tar:build_failed.log`: captured build failure from the validation environment.\n\nThe PoC configures a blocking exporter and a `BatchingProcessor` with `WithExportMaxBatchSize(1)`, `WithExportInterval(5*time.Second)`, and `WithMaxQueueSize(2048)`. It emits 1000 records, records a CPU profile for 750 ms while the exporter is blocked, then writes `/workspace/validation_artifacts/busyloop.pprof`.\n\nReproduction steps from an affected checkout at commit `4af9c20`:\n\n```sh\ncd /workspace/opentelemetry-go\ngit checkout 4af9c20\n\nmkdir -p validation_poc/busyloop /workspace/validation_artifacts /tmp/batchingprocessor-busyloop-poc\ntar -xf /path/to/this/finding/validation-artifact.tar -C /tmp/batchingprocessor-busyloop-poc\ncp /tmp/batchingprocessor-busyloop-poc/main.go validation_poc/busyloop/main.go\n\ngo build -o validation_poc/busyloop/busyloop ./validation_poc/busyloop\n./validation_poc/busyloop/busyloop\ngo tool pprof -top /workspace/validation_artifacts/busyloop.pprof\n```\n\nExpected program output:\n\n```text\ncpu profile written to /workspace/validation_artifacts/busyloop.pprof\n```\n\nExpected profile evidence: hot functions should include `(*BatchingProcessor).poll`, `(*queue).TryDequeue`, and `(*bufferExporter).EnqueueExport`, showing repeated export attempts while the exporter is blocked.\n\n\n### Impact\n\nThis is an availability vulnerability: uncontrolled CPU consumption caused by a busy-spin retry loop. Applications using `sdk/log` `BatchingProcessor` are impacted when an attacker can cause sustained log emission and the configured exporter or downstream collector is slow, blocked, or otherwise backpressured. The impact is limited to the embedding process but can degrade or deny service for that application.",
  "id": "GHSA-hjf4-fphr-2h65",
  "modified": "2026-09-29T17:59:53Z",
  "published": "2026-09-29T17:59:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-hjf4-fphr-2h65"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81872"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/issues/6797"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/pull/8620"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/commit/ba71b09e6ed272e93a669aeaec1e98b1df4cc582"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-telemetry/opentelemetry-go"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/log/v0.21.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full"
}

CVE-2026-81872 (GCVE-0-2026-81872)

Vulnerability from cvelistv5 – Published: 2026-09-16 20:42 – Updated: 2026-09-17 13:36

Title

OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full

Summary

OpenTelemetry-Go is the Go implementation of OpenTelemetry. Prior to version 0.21.0, the go.opentelemetry.io/otel/sdk/log BatchingProcessor can enter a tight CPU loop when attacker-driven log emission fills its asynchronous export buffer while the exporter is backpressured. NewBatchingProcessor wraps the exporter with newBufferExporter(exporter, 1), and the poll loop calls queue.TryDequeue and bufferExporter.EnqueueExport before immediately signaling pollTrigger whenever the queue remains at or above batchSize. Because a failed nonblocking EnqueueExport leaves the queue length unchanged, the processor repeatedly retries without waiting for its ticker, exhausting CPU and degrading or denying service in the embedding process. This issue is fixed in version 0.21.0.

Severity

6.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-17 13:36 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption
CWE-834 - Excessive Iteration

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/open-telemetry/opentelemetry-g…	x_refsource_CONFIRM
https://github.com/open-telemetry/opentelemetry-g…	x_refsource_MISC
https://github.com/open-telemetry/opentelemetry-g…	x_refsource_MISC
https://github.com/open-telemetry/opentelemetry-g…	x_refsource_MISC
https://github.com/open-telemetry/opentelemetry-g…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
open-telemetry	opentelemetry-go	Affected: < 0.21.0

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-81872",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-17T13:36:11.140898Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-17T13:36:27.289Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-hjf4-fphr-2h65"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "opentelemetry-go",
          "vendor": "open-telemetry",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.21.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "OpenTelemetry-Go is the Go implementation of OpenTelemetry. Prior to version 0.21.0, the go.opentelemetry.io/otel/sdk/log BatchingProcessor can enter a tight CPU loop when attacker-driven log emission fills its asynchronous export buffer while the exporter is backpressured. NewBatchingProcessor wraps the exporter with newBufferExporter(exporter, 1), and the poll loop calls queue.TryDequeue and bufferExporter.EnqueueExport before immediately signaling pollTrigger whenever the queue remains at or above batchSize. Because a failed nonblocking EnqueueExport leaves the queue length unchanged, the processor repeatedly retries without waiting for its ticker, exhausting CPU and degrading or denying service in the embedding process. This issue is fixed in version 0.21.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-834",
              "description": "CWE-834: Excessive Iteration",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T20:42:23.507Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-hjf4-fphr-2h65",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-hjf4-fphr-2h65"
        },
        {
          "name": "https://github.com/open-telemetry/opentelemetry-go/issues/6797",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-telemetry/opentelemetry-go/issues/6797"
        },
        {
          "name": "https://github.com/open-telemetry/opentelemetry-go/pull/8620",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-telemetry/opentelemetry-go/pull/8620"
        },
        {
          "name": "https://github.com/open-telemetry/opentelemetry-go/commit/ba71b09e6ed272e93a669aeaec1e98b1df4cc582",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-telemetry/opentelemetry-go/commit/ba71b09e6ed272e93a669aeaec1e98b1df4cc582"
        },
        {
          "name": "https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/log/v0.21.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/log/v0.21.0"
        }
      ],
      "source": {
        "advisory": "GHSA-hjf4-fphr-2h65",
        "discovery": "UNKNOWN"
      },
      "title": "OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-81872",
    "datePublished": "2026-09-16T20:42:23.507Z",
    "dateReserved": "2026-08-27T17:48:42.121Z",
    "dateUpdated": "2026-09-17T13:36:27.289Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

GHSA-HJF4-FPHR-2H65

Summary

Details

PoC

Impact

CVE-2026-81872 (GCVE-0-2026-81872)

Tags

Sightings

Nomenclature

Related by attack behaviour