CVE-2026-50018: SpectoLabs Hoverfly denial of service via goroutine leak in post-serve actions

CVE-2026-50018 · Severity: medium · CVSS 6.5 · Published 2026-09-11

Hoverfly is a service virtualization tool used for API simulation and testing. A vulnerability in how it handles remote post-serve actions allows an attacker to crash the service by exhausting its memory. By directing the tool to a non-responsive web address, an attacker can cause the system to freeze or shut down, disrupting development and testing workflows.

Technologies: github.com/SpectoLabs/hoverfly (Go). Vendors: Go.

Quick answers

Is CVE-2026-50018 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-50018 being exploited in the wild.
How severe is CVE-2026-50018?
Medium severity, with a CVSS score of 6.5, published 11 September 2026.
Which products and versions are affected?
github.com/SpectoLabs/hoverfly (Go) <= 1.12.7, SEMVER:introduced=0,fixed=1.12.8; SpectoLabs Hoverfly <= 1.12.7.
Is there a fix for CVE-2026-50018?
Yes. github.com/SpectoLabs/hoverfly (Go): upgrade to 1.12.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-50018 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-50018?
Check whether you run github.com/SpectoLabs/hoverfly (Go) or SpectoLabs Hoverfly 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

  • github.com/SpectoLabs/hoverfly (Go): upgrade to 1.12.8 or later
    go get github.com/SpectoLabs/hoverfly@v1.12.8

Technical details

A goroutine leak exists in Hoverfly's remote post-serve action execution. The component uses Go's `http.DefaultClient`, which lacks a default timeout, to perform POST requests to remote endpoints. When a remote action is triggered against a non-responsive or 'black-hole' server, the spawned goroutine blocks indefinitely. Because there is no limit on the number of concurrent goroutines or a mechanism for backpressure, an attacker can flood the proxy with requests to cause unbounded memory consumption and an eventual Out-of-Memory (OOM) crash. This is exploitable if the attacker has access to the admin API to register the malicious action. The issue is fixed in version 1.12.8.

Affected products

  • SpectoLabs hoverfly <= 1.12.7

Identifiers

  • CVE-2026-50018
  • GHSA-42j2-w334-qxw7
  • GO-2026-5975

Timeline

  • 2026-06-03: disclosed: Initial disclosure to SpectoLabs
  • 2026-07-14: advisory: GitHub Advisory published
  • 2026-07-14: patched: Version 1.12.8 released

References

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