Summary
OpenTelemetry-Go: Unsynchronized baggage map can panic under concurrent access
go.opentelemetry.io/otel/bridge/opentracing introduced an unsynchronized extraBaggageItems map on bridgeSpan. One goroutine can write this map through Span.SetBaggageItem while another goroutine reads and iterates it during correlation baggage propagation, which can trigger Go's fatal concurrent map access panic and crash the process. The finding is low severity because exploitation requires a specific OpenTracing bridge configuration and concurrent use of the same span.
Introduced in commit: 8cddf30
Details
bridge/opentracing/bridge.go:80-85 adds extraBaggageItems map[string]string to bridgeSpan without a mutex or other synchronization primitive. bridge/opentracing/bridge.go:219-234 shows SetBaggageItem calling updateOtelContext, which lazily creates the map and writes s.extraBaggageItems[restrictedKey] = value without locking. bridge/opentracing/bridge.go:359-377 shows correlationGetHook reading bSpan.extraBaggageItems, checking len(items), and iterating for k, v := range items without locking. The finding evidence also identifies api/correlation/context.go:160-165 as the path where correlation.MapFromContext invokes the get hook, allowing a read path to run concurrently with baggage writes.
Because Go maps are not safe for concurrent read/write access, concurrent SetBaggageItem and correlation.MapFromContext calls on the same hooked bridgeSpan can terminate the process with a runtime error such as fatal error: concurrent map read and map write or fatal error: concurrent map iteration and map write.
PoC
The validation artifact contains a PoC at validation-artifact.tar:validation_poc_concurrent_map.go and supporting notes at validation-artifact.tar:validation_poc_README.txt.
Use a checkout of pellared/opentelemetry-go at commit 8cddf30 with Go module downloads enabled. The local validation environment could not complete the run because GOPROXY=off blocked dependency resolution; that blocked output is saved in validation-artifact.tar:validation_poc_run.log.
Commands:
cd /path/to/opentelemetry-go
git checkout 8cddf30
tar -xOf /path/to/finding-directory/validation-artifact.tar validation_poc_concurrent_map.go > ./validation_poc_concurrent_map.go
GOPROXY=https://proxy.golang.org,direct go run ./validation_poc_concurrent_map.go
The PoC starts a BridgeTracer, creates a span, installs correlation hooks with tracer.NewHookedContext(ctx), initializes baggage once, then runs one goroutine repeatedly calling span.SetBaggageItem(...) while another repeatedly calls otelcorrelation.MapFromContext(ctx). A vulnerable build is expected to terminate with a Go runtime concurrent map access error, for example:
fatal error: concurrent map read and map write
or:
fatal error: concurrent map iteration and map write
Impact
This is a race condition / improper synchronization vulnerability in a shared Go map. Applications using the OpenTelemetry OpenTracing bridge with correlation hooks can crash if the same bridgeSpan is accessed concurrently, with one execution path setting baggage and another propagating correlation baggage. The practical impact is denial of service for the affected application process; exposure depends on whether application request handling or internal concurrency can trigger those operations on the same span.
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is CVE-2026-45404? CVE-2026-45404 is a medium-severity race condition vulnerability in go.opentelemetry.io/otel/bridge/opentracing (go), affecting versions >= 0.11.0, < 1.45.0. It is fixed in 1.45.0. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- Which versions of go.opentelemetry.io/otel/bridge/opentracing are affected by CVE-2026-45404? go.opentelemetry.io/otel/bridge/opentracing (go) versions >= 0.11.0, < 1.45.0 is affected.
- Is there a fix for CVE-2026-45404? Yes. CVE-2026-45404 is fixed in 1.45.0. Upgrade to this version or later.
- Is CVE-2026-45404 exploitable, and should I be worried? Whether CVE-2026-45404 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-45404 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-45404? Upgrade
go.opentelemetry.io/otel/bridge/opentracingto 1.45.0 or later.