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

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

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.

Source published

16 Sep 2026 20:42:23 UTC

Source modified

17 Sep 2026 13:36:27 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 6.3 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

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 wh…

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.

Source published

Sep 16, 2026, 8:42:23 PM (timezone not stated)

Source modified

Sep 17, 2026, 1:36:27 PM (timezone not stated)

Saved here

11 Nov 2026 16:10:33 UTC

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EUVD CVSS 4.0 · 6.3 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

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 wh…

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.

Source published

16 Sep 2026 21:17:22 UTC

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30 Sep 2026 17:43:24 UTC

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25 Oct 2026 16:19:10 UTC

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CVSS 4.0 · [email protected] · Secondary · 6.3 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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

### 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](https://github.com/user-attachments/files/27494002/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`: ```sh 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: ```text 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.

Source published

29 Sep 2026 17:59:53 UTC

Source modified

1 Oct 2026 20:56:06 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V4 · 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

Publisher rating · MODERATE

OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full in go.opentelemetry.io/otel/sdk/log

OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full in go.opentelemetry.io/otel/sdk/log

Source published

1 Oct 2026 20:24:10 UTC

Source modified

1 Oct 2026 20:45:14 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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OSV · upstream source license applies

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Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.