Advisoriesby IbisUnbounded W3C tracestate parsing may lead to DoS
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.
References
W3C Trace Context specification, tracestate field:
- https://www.w3.org/TR/trace-context/#tracestate-header-field-values
- https://www.w3.org/TR/trace-context/#tracestate-limits
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| datadog-opentelemetry crates.io | >= 0.1.0, < 0.3.3 | 0.3.3 |
Details and references
### 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. ### References W3C Trace Context specification, `tracestate` field: - https://www.w3.org/TR/trace-context/#tracestate-header-field-values - https://www.w3.org/TR/trace-context/#tracestate-limits
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Severity from
- GitHub (reviewed advisory)