Swift W3C TraceContext has malformed HTTP header that can cause a crash
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
Swift W3C TraceContext is a Swift implementation of the W3C Trace Context standard, and Swift OTel is an OpenTelemetry Protocol (OTLP) backend for Swift Log, Swift Metrics, and Swift Distributed Tracing. Prior to Swift W3C TraceContext version 1.0.0-beta.5 and Swift OTel version 1.0.4, a denial-of-service vulnerability due to improper input validation allows a remote attacker to crash the service via a malformed HTTP header. This allows crashing the process with data coming from the network when used with, for example, an HTTP server. Most common way of using Swift W3C Trace Context is through Swift OTel. Version 1.0.0-beta.5 of Swift W3C TraceContext and version 1.0.4 of Swift OTel contain a patch for this issue. As a workaround, disable either Swift OTel or the code that extracts the trace information from an incoming header (such as a `TracingMiddleware`).
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| swift-otel | swift-w3c-trace-context | swift-otel < 1.0.4; swift-w3c-trace-context < 1.0.0-beta.5 | — | No fix listed | CNA |
| — | github.com/swift-otel/swift-w3c-trace-context (SwiftURL) | before 1.0.0-beta.5 | 1.0.0-beta.5 | Patch available | GHSA-mvpq-2v8x-ww6g |
| — | github.com/swift-otel/swift-otel (SwiftURL) | before 1.0.4 | 1.0.4 | Patch available | GHSA-mvpq-2v8x-ww6g |
- swift-w3c-trace-context Vendorswift-otel Affected swift-otel < 1.0.4; swift-w3c-trace-context < 1.0.0-beta.5 Fixed in — No fix listed CNA
- github.com/swift-otel/swift-w3c-trace-context (SwiftURL) Vendor— Affected before 1.0.0-beta.5 Fixed in 1.0.0-beta.5 Patch available GHSA-mvpq-2v8x-ww6g
- github.com/swift-otel/swift-otel (SwiftURL) Vendor— Affected before 1.0.4 Fixed in 1.0.4 Patch available GHSA-mvpq-2v8x-ww6g
Remediation
- Fix · GHSA-mvpq-2v8x-ww6g github.com/swift-otel/swift-w3c-trace-context (SwiftURL) Fixed in 1.0.0-beta.5 Advisory →
- Fix · GHSA-mvpq-2v8x-ww6g github.com/swift-otel/swift-otel (SwiftURL) Fixed in 1.0.4 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-23886
- 2026-10-03 Alias added: GHSA-mvpq-2v8x-ww6g
References
Other 5
- https://github.com/swift-otel/swift-w3c-trace-context/security/advisories/GHSA-mvpq-2v8x-ww6g
- https://github.com/swift-otel/swift-w3c-trace-context/commit/5da9b143ba6046734de3fa51dafea28290174e4e
- https://github.com/swift-otel/swift-otel/releases/tag/1.0.4
- https://github.com/swift-otel/swift-w3c-trace-context/releases/tag/1.0.0-beta.5
- https://github.com/swift-otel/swift-w3c-trace-context
Sources
- CVE-2026-23886 · CVE Program
- CVE-2026-23886 · NVD
- FIRST EPSS
- GHSA-mvpq-2v8x-ww6g · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences