dd-trace-rs provides Datadog application performance monitoring for Rust. From 0.1.0 until 0.3.3, datadog-opentelemetry/src/propagation/tracecontext.rs parses the W3C tracestate header and collects every semicolon-separated key and value pair in the Datadog dd=... vendor entry into a HashMap without enforcing a pair count or entry size limit. Because tracecontext extraction is enabled by default, a remote unauthenticated attacker can send an arbitrarily large dd=... entry and force excessive CPU and memory consumption for each request, causing denial of service in an instrumented network service. This vulnerability is fixed in 0.3.3.

Affected: crates.io: datadog-opentelemetry

### Impact Datadog tracing libraries that implement W3C Trace Context (`tracecontext`) propagation parse the incoming `tracestate` header without enforcing a size cap on the Datadog vendor entry (`dd=...`). The `dd=` value contains semicolon-separated `key:value` pairs, and the parser allocates a hash-map entry for each pair. A remote, unauthenticated attacker can send a `tracestate` header whose `dd=` member is arbitrarily large (or contains an arbitrarily large number of pairs), forcing unbounded CPU and memory consumption per request and enabling a remote Denial of Service. `tracecontext` extraction is enabled by default in affected tracers, so any internet-facing service instrumented with an affected version is exposed unless `tracecontext` has been explicitly removed from the propagation style configuration.

### Patches This is resolved in version 0.3.3 and later of the `dd-trace-rs` library.

### Workarounds If you cannot upgrade immediately: 1. Disable `tracecontext` extraction by setting `DD_TRACE_PROPAGATION_STYLE_EXTRACT` to a value that does not include `tracecontext` (for example, `datadog`). 2. Cap the maximum HTTP request header size at an upstream proxy or web server.