---
id: CVE-2026-50018
title: Hoverfly is an open source API simulation tool
summary: >-
  Hoverfly is an open source API simulation tool. Prior to version 1.12.8,
  remote post-serve actions use `http.DefaultClient` without any timeout
  configuration. When the remote endpoint is unreachable or intentionally slow
  (accepts TCP con…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-770
vendor: SpectoLabs
product: hoverfly
affected:
  - hoverfly < 1.12.8
patched:
  - github.com/SpectoLabs/hoverfly 1.12.8
published: '2026-09-11'
updated: '2026-09-14'
sourceUpdated: '2026-09-14T20:16:44.783'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-50018'
references:
  - url: 'https://github.com/SpectoLabs/hoverfly/pull/1228'
    label: security-advisories@github.com
  - url: 'https://github.com/SpectoLabs/hoverfly/releases/tag/v1.12.8'
    label: security-advisories@github.com
  - url: >-
      https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-42j2-w334-qxw7
    label: security-advisories@github.com
  - url: >-
      https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-42j2-w334-qxw7
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/advisories/GHSA-42j2-w334-qxw7'
tags:
  - nvd
  - cve.org
  - exploit-available
  - ghsa
  - go
epss: 0.00543
epssPercentile: 0.43257
aliases:
  - GHSA-42j2-w334-qxw7
ecosystem: go
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T19:28:24.142551Z'
ingestedAt: '2026-07-14T18:38:32.931Z'
---

## Overview

Hoverfly is an open source API simulation tool. Prior to version 1.12.8, remote post-serve actions use `http.DefaultClient` without any timeout configuration. When the remote endpoint is unreachable or intentionally slow (accepts TCP connection but never responds), each triggered proxy request spawns a goroutine that blocks indefinitely on `http.DefaultClient.Do()`. An attacker can cause unbounded goroutine accumulation leading to memory exhaustion and process crash (OOM kill). Unlike local post-serve action execution, this requires no binary execution, only a URL pointing to a non-responsive endpoint. Version 1.12.8 patches the issue.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-50018)

Affected packages:

- `github.com/SpectoLabs/hoverfly <= 1.12.7`

Patched in:

- `github.com/SpectoLabs/hoverfly 1.12.8`

Source: https://github.com/advisories/GHSA-42j2-w334-qxw7