CVE-2026-41178: OpenTelemetry-Go Denial of Service via oversized baggage headers

CVE-2026-41178 · Severity: medium · CVSS 5.3 · Published 2026-06-04

OpenTelemetry-Go is a software library used by developers to monitor and trace the performance of Go applications. A vulnerability in how the library handles 'baggage' headers—metadata passed between services—allows a remote attacker to send specially crafted, oversized headers that the system will attempt to process and log. This can lead to a denial-of-service (DoS) condition where the application's performance is degraded due to excessive CPU usage or its storage is filled with large volumes of error logs.

Vendors: Go, Opentelemetry.

Quick answers

Is CVE-2026-41178 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-41178 being exploited in the wild.
How severe is CVE-2026-41178?
Medium severity, with a CVSS score of 5.3, published 4 June 2026.
Which products and versions are affected?
go.opentelemetry.io/otel (Go) SEMVER:introduced=1.41.0,fixed=1.42.0,introduced=1.43.0,fixed=1.44.0; go.opentelemetry.io/otel/baggage (Go) SEMVER:introduced=1.41.0,fixed=1.42.0; go.opentelemetry.io/otel/propagation (Go) SEMVER:introduced=1.41.0,fixed=1.42.0; Opentelemetry Baggage API/SDK 1.41.0, 1.43.0; and 3 more.
Is there a fix for CVE-2026-41178?
Yes. go.opentelemetry.io/otel (Go): upgrade to 1.44.0 or later; go.opentelemetry.io/otel/baggage (Go): upgrade to 1.42.0 or later; go.opentelemetry.io/otel/propagation (Go): upgrade to 1.42.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-41178 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-41178?
Check whether you run go.opentelemetry.io/otel (Go), go.opentelemetry.io/otel/baggage (Go), go.opentelemetry.io/otel/propagation (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • go.opentelemetry.io/otel (Go): upgrade to 1.44.0 or later
    go get go.opentelemetry.io/otel@v1.44.0
  • go.opentelemetry.io/otel/baggage (Go): upgrade to 1.42.0 or later
    go get go.opentelemetry.io/otel/baggage@v1.42.0
  • go.opentelemetry.io/otel/propagation (Go): upgrade to 1.42.0 or later
    go get go.opentelemetry.io/otel/propagation@v1.42.0

Technical details

A regression in OpenTelemetry-Go versions 1.41.0 and 1.43.0 removed raw-length rejection and per-member size guards during baggage header parsing. The `Parse` function in `baggage/baggage.go` now iterates over all list members using `strings.SplitSeq` and performs full tokenization and `PathUnescape` decoding on each member without early rejection of oversized inputs. Furthermore, `propagation/baggage.go` forwards these parsing errors to the global error handler, which typically defaults to logging. An unauthenticated remote attacker can exploit this by sending malformed or extremely large baggage headers, leading to CPU exhaustion and log disk space exhaustion. The issue is mitigated by transport-level header limits but remains a risk for services with high limits or default error handling.

Affected products

  • OpenTelemetry opentelemetry-go (go.opentelemetry.io/otel/baggage) 1.41.0, 1.43.0
  • OpenTelemetry opentelemetry-go (go.opentelemetry.io/otel/propagation) 1.41.0, 1.43.0

Identifiers

  • CVE-2026-41178
  • GHSA-5wrp-cwcj-q835
  • GO-2026-5158

Timeline

  • 2026-02-28: patched: Initial PR to comply with W3C limits merged
  • 2026-05-28: advisory: GitHub Security Advisory published
  • 2026-06-04: disclosed: CVE published to NVD

References

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