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opentelemetry_sdk has unbounded memory allocation in W3C Baggage propagation

Moderate severity GitHub Reviewed Published May 26, 2026 in open-telemetry/opentelemetry-rust • Updated Jun 25, 2026

Package

opentelemetry_sdk (Rust)

Affected versions

<= 0.32.0

Patched versions

0.32.1

Description

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

Credit

tonghuaroot

References

@trask trask published to open-telemetry/opentelemetry-rust May 26, 2026
Published to the GitHub Advisory Database Jun 25, 2026
Reviewed Jun 25, 2026
Last updated Jun 25, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(27th percentile)

Weaknesses

Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. Learn more on MITRE.

CVE ID

CVE-2026-48504

GHSA ID

GHSA-w9wp-h8wv-79jx

Credits

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