CVE-2026-50276 in dd-trace-rb
Summary
by MITRE • 09/14/2026
dd-trace-rb is Datadog's client library for Ruby. Prior to 2.32.0, W3C baggage extraction does not enforce DD_TRACE_BAGGAGE_MAX_ITEMS, which defaults to 64, or DD_TRACE_BAGGAGE_MAX_BYTES, which defaults to 8192, although those limits apply during baggage injection. A remote unauthenticated attacker can send a baggage HTTP header containing many comma-separated key-value pairs or a single very large value. The extraction path allocates entries while parsing the attacker-controlled header on every request, causing unbounded CPU and memory consumption in an HTTP service where the baggage propagation style is enabled, which is the default for most affected tracers. This can cause denial of service. This issue is fixed in version 2.32.0.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified within Datadog's dd-trace-rb library prior to version 2.32.0 represents a significant resource exhaustion flaw rooted in the asymmetric enforcement of configuration limits during distributed tracing operations. Specifically, while the injection path for W3C baggage correctly adheres to the DD_TRACE_BAGGAGE_MAX_ITEMS and DD_TRACE_BAGGAGE_MAX_BYTES environment variables, which default to sixty-four items and eight thousand one hundred ninety-two bytes respectively, the extraction path fails to apply these same constraints. This discrepancy creates a critical security gap where an attacker can exploit the lack of validation during the parsing phase to trigger unbounded resource consumption on the server side. The vulnerability is particularly severe because W3C baggage propagation is enabled by default in most affected tracers, meaning that any service instrumented with this library and configured for distributed tracing is potentially susceptible without requiring additional configuration changes from the operator.
From a technical perspective, the flaw lies in how the HTTP client or server processes incoming headers containing trace context data. When an attacker sends a malicious HTTP request featuring a baggage header populated with numerous comma-separated key-value pairs or a single excessively large value, the extraction logic iterates through these entries and allocates memory for each one without checking against the predefined maximums. This process occurs on every affected request, leading to continuous allocation of heap space and CPU cycles dedicated to parsing and storing unnecessary data structures. In high-throughput environments, this behavior can rapidly deplete available system resources, causing the application thread pool to become exhausted or triggering out-of-memory errors that crash the service. The impact is a classic denial of service scenario where legitimate traffic cannot be processed due to resource contention caused by malicious input parsing overhead.
This vulnerability aligns with CWE-787 Out-of-bounds Write and more specifically CWE-400 Uncontrolled Resource Consumption, as the application fails to limit the amount of resources it consumes in response to user input. In terms of offensive security frameworks such as MITRE ATT&CK, this behavior is characteristic of T1496 Resource Hijacking or potentially part of a broader Denial of Service campaign under T1499 Endpoint Disruption if the exhaustion leads to system-wide instability. The attack vector is remote and unauthenticated, requiring only network access to send HTTP requests with crafted headers, which significantly lowers the barrier for exploitation compared to vulnerabilities that require authentication or specific application states beyond standard operation.
Mitigation strategies primarily involve upgrading the dd-trace-rb library to version 2.32.0 or later, where the extraction logic has been patched to enforce the same limits as injection. For organizations unable to immediately patch their dependencies, temporary mitigations may include implementing web application firewall rules that inspect and truncate HTTP baggage headers exceeding a reasonable size threshold before they reach the Ruby application layer. Additionally, operators can consider disabling W3C baggage propagation if it is not strictly required for their distributed tracing architecture, although this would impact trace continuity across services using standard-compliant tracers. Regular monitoring of memory usage patterns in instrumented services should also be maintained to detect any anomalous spikes that might indicate ongoing exploitation attempts or other resource exhaustion vulnerabilities.