Medium severity · published Sep 11, 2026
CVE-2026-50018
Hoverfly: Denial of Service via Goroutine Leak in Remote Post-Serve Actions
6.5
CVSS
0.5%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hoverfly · SpectoLabs
< 1.12.8 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-50018
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-50018
github.com
https://github.com/SpectoLabs/hoverfly/pull/1228
github.com
https://github.com/SpectoLabs/hoverfly/releases/tag/v1.12.8
github.com
https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-42j2-w334-qxw7
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