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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-48504 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-48504 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-48504. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-48504 in your dependencies?
O3 Security finds CVE-2026-48504 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.