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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

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 · score source

EPSS

• CVE-2026-81872: 0.38% estimated exploitation activity in the next 30 days; percentile 32.40 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

29 Sep 2026, 17:59 UTC

Last modified by the source

1 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-hjf4-fphr-2h65

2. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6615

4. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-hjf4-fphr-2h65

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-81872

Advisory: OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full
IDs: CVE-2026-81872, GHSA-hjf4-fphr-2h65
Record: https://patchnext.com/advisories/cve-2026-81872 (revision 4, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: go.opentelemetry.io/otel/sdk/log 0.21.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go go.opentelemetry.io/otel/sdk/log: affected < 0.21.0; fixed in 0.21.0

## Suggested inspection (read-only)
- Go go.opentelemetry.io/otel/sdk/log: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on go.opentelemetry.io/otel/sdk/log.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6615 (OSV record GO-2026-6615 lists affected ranges: Go go.opentelemetry.io/otel/sdk/log >=0 <0.21.0 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-hjf4-fphr-2h65 (OSV record GHSA-hjf4-fphr-2h65 lists affected ranges: Go go.opentelemetry.io/otel/sdk/log >=0 <0.21.0 (fixed))
- Verified: https://github.com/advisories/GHSA-hjf4-fphr-2h65 (GitHub-reviewed advisory GHSA-hjf4-fphr-2h65 lists affected ranges: Go go.opentelemetry.io/otel/sdk/log >=0 <0.21.0)

Commands are suggestions: review each one before running it.