opentelemetry_sdk has unbounded memory allocation in W3C Baggage propagation

Summary

BaggagePropagator::extract_with_context in opentelemetry_sdk did not enforce the W3C Baggage size limits before parsing an inbound baggage header. A large attacker-controlled header could cause unnecessary CPU work and short-lived heap allocations while parsing entries that would later be discarded by the SDK's baggage storage limits.

The SDK now applies limits aligned with the W3C Baggage limits:

• 64 list-members
• 8192 bytes total

Impact

Services that accept untrusted inbound propagation headers may experience increased per-request resource usage when processing oversized baggage headers. This can contribute to denial-of-service risk, especially when application or transport-level header limits are absent or configured above the W3C Baggage limits.

The impact is limited to availability. This issue does not expose telemetry data, modify telemetry data, or allow code execution.

Patches

Upgrade opentelemetry_sdk to version 0.32.1 or later.

Version 0.32.1 rejects baggage header values larger than 8192 bytes and limits extraction to the first 64 list-members.

Workarounds

If upgrading immediately is not possible, reject or limit inbound baggage headers larger than 8192 bytes before invoking OpenTelemetry propagation extraction. This can be enforced at a proxy, gateway, middleware layer, or custom carrier boundary.

Resources

• W3C Baggage limits: https://www.w3.org/TR/baggage/#limits
• Related OpenTelemetry Java advisory: https://github.com/open-telemetry/opentelemetry-java/security/advisories/GHSA-rcgg-9c38-7xpx
• Related OpenTelemetry Go advisory: https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-mh2q-q3fh-2475
• CVE-2026-48504

Credit

tonghuaroot