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

Source: https://junglewise.ai/threats/cve-2026-50018-spectolabs-hoverfly-denial-of-service-via-goroutine-leak-in-post  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-spectolabs-hoverfly). Vendors: [Go](https://junglewise.ai/threats/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

  ```sh
  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

- [https://api.github.com/users/Kr1shna4garwal](https://api.github.com/users/Kr1shna4garwal)
- [https://github.com/Kr1shna4garwal](https://github.com/Kr1shna4garwal)
- [https://api.github.com/users/Kr1shna4garwal/gists%7B/gist_id%7D](https://api.github.com/users/Kr1shna4garwal/gists%7B/gist_id%7D)
- [https://api.github.com/users/Kr1shna4garwal/repos](https://api.github.com/users/Kr1shna4garwal/repos)
- [https://avatars.githubusercontent.com/u/85845881?v=4](https://avatars.githubusercontent.com/u/85845881?v=4)
- [https://api.github.com/users/Kr1shna4garwal/events%7B/privacy%7D](https://api.github.com/users/Kr1shna4garwal/events%7B/privacy%7D)

## Related threats

- [SpectoLabs Hoverfly race condition in Diff mode](https://junglewise.ai/threats/cve-2026-50013-spectolabs-hoverfly-race-condition-in-diff-mode)
- [WebSocket endpoint `/api/v2/ws/logs` reachable without authentication even when --auth is enabled](https://junglewise.ai/threats/cve-2025-54376-websocket-endpoint-api-v2-ws-logs-reachable-without)
- [Hoverfly is vulnerable to Remote Code Execution through an insecure middleware implementation](https://junglewise.ai/threats/cve-2025-54123-hoverfly-is-vulnerable-to-remote-code-execution-through-an)
- [Hoverfly allows an arbitrary file read in the `/api/v2/simulation` endpoint (`GHSL-2023-274`)](https://junglewise.ai/threats/cve-2024-45388-hoverfly-allows-an-arbitrary-file-read-in-the-api-v2-simulation)