CVE-2026-23886
📋 TL;DR
A denial-of-service vulnerability in Swift W3C TraceContext and Swift OTel allows remote attackers to crash services by sending malformed HTTP headers. This affects systems using these libraries for distributed tracing, particularly when exposed to untrusted network traffic. The vulnerability is exploitable without authentication via HTTP requests.
💻 Affected Systems
- Swift W3C TraceContext
- Swift OTel
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage with process crashes, leading to downtime and potential data loss in affected applications.
Likely Case
Service disruption and availability issues when attackers send crafted HTTP headers to vulnerable endpoints.
If Mitigated
No impact if patched versions are used or workarounds are implemented to filter malicious headers.
🎯 Exploit Status
Exploitation requires network access to services using vulnerable libraries. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Swift W3C TraceContext 1.0.0-beta.5, Swift OTel 1.0.4
Vendor Advisory: https://github.com/swift-otel/swift-w3c-trace-context/security/advisories/GHSA-mvpq-2v8x-ww6g
Restart Required: Yes
Instructions:
1. Update Swift W3C TraceContext to version 1.0.0-beta.5 or later. 2. Update Swift OTel to version 1.0.4 or later. 3. Restart affected services. 4. Verify the update using package manager commands.
🔧 Temporary Workarounds
Disable trace header processing
allRemove or disable code that extracts trace information from HTTP headers, such as TracingMiddleware.
Modify application code to remove TracingMiddleware or similar trace extraction components
Disable Swift OTel
allTemporarily disable Swift OTel integration if not critical for operations.
Remove Swift OTel dependencies or disable OTel initialization in application code
🧯 If You Can't Patch
- Implement WAF rules to block malformed trace context headers
- Use reverse proxies to sanitize or drop suspicious HTTP headers before reaching vulnerable services
🔍 How to Verify
Check if Vulnerable:
Check Package.swift or Package.resolved for Swift W3C TraceContext version < 1.0.0-beta.5 or Swift OTel version < 1.0.4Check Version:
swift package show-dependencies | grep -E '(swift-w3c-trace-context|swift-otel)'Verify Fix Applied:
Confirm Swift W3C TraceContext >= 1.0.0-beta.5 and Swift OTel >= 1.0.4 in dependencies, then test with malformed trace headers📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes
- HTTP 500 errors after receiving trace headers
- Application restarts following HTTP requests
Network Indicators:
- HTTP requests with malformed traceparent or tracestate headers
- Unusual header patterns in incoming requests
SIEM Query:
source="application_logs" AND ("crash" OR "panic") AND "trace" AND "header"🔗 References
- https://github.com/swift-otel/swift-otel/releases/tag/1.0.4
- https://github.com/swift-otel/swift-w3c-trace-context/commit/5da9b143ba6046734de3fa51dafea28290174e4e
- 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/security/advisories/GHSA-mvpq-2v8x-ww6g
