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This vulnerability exists in the library’s parsing logic for the `traceparent` HTTP header, used for distributed tracing. The function that extracts and validates the header’s fields (version, trace-id, parent-id, trace-flags) does not properly handle all cases of malformed input. Specifically, when a header with an invalid format or incorrect length is received, the parser attempts to access string indices or components that do not exist. This leads to a runtime error, such as a forced unwrap of a `nil` value or an index-out-of-bounds crash, immediately terminating the process. As the library is often integrated via Swift OTel’s middleware in HTTP servers, a single malicious HTTP request containing a malformed `traceparent` header can crash the entire application.
DailyCVE Form:
Platform: Swift W3C TraceContext
Version: 1.0.0-beta.5
Vulnerability: Header Parsing DoS
Severity: Moderate
Date: 2026-01-19
Prediction: Patch expected 2026-01-26
What Undercode Say:
Simulating a malicious request with a malformed traceparent header curl -H "traceparent: 00-invalid" http://target.server/
// Code snippet showing vulnerable header extraction path let header = request.headers["traceparent"] // Malformed input crashes here
// Immediate workaround: Disable the tracing middleware // let app = Application() // app.middleware = [/ Removed: TracingMiddleware() /]
How Exploit:
Send HTTP request with malformed `traceparent` header like `00-invalid` or an incorrectly shortened string to a vulnerable endpoint using Swift OTel.
Protection from this CVE:
Update to patched version. Apply workaround: disable `TracingMiddleware`.
Impact:
Remote Denial-of-Service (application crash).
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
