CVE-2026-48504 is a medium-severity (CVSS 5.3) CWE-770 vulnerability in opentelemetry_sdk. A fix is available for opentelemetry_sdk — see the affected versions and patch details below.
OpenTelemetry Rust: Unbounded memory allocation in W3C Baggage propagation
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48504.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
opentelemetry_sdkReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
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
- 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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | opentelemetry_sdk | all versions | 0.32.1cargo update -p opentelemetry_sdk --precise 0.32.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for opentelemetry_sdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update opentelemetry_sdk to 0.32.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48504 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2026-48504 in your dependencies?
Find it across crates.io, including transitive dependencies.