CVE-2026-50013

Hoverfly: Process Crash via Concurrent Map Write Race Condition in Diff Mode

State: Published
Severity: 7.5 High
Published: Sep 11, 2026
Updated: Sep 14, 2026
Reserved: Jun 2, 2026

Description

Hoverfly is an open source API simulation tool. Prior to version 1.12.8, when Hoverfly is running in Diff mode, the `AddDiff()` function writes to the shared `responsesDiff` map without any synchronization (no mutex). When multiple proxy requests are processed concurrently (the normal case for any proxy), the concurrent map writes trigger Go's built-in race detector which causes a `fatal error: concurrent map read and map write`, immediately killing the entire Hoverfly process. This is trivially exploitable by sending multiple simultaneous requests. Version 1.12.8 patches the issue.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	GitHub_M

Weaknesses

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-820 Missing Synchronization

Affected Products

Product	Versions
hoverflySpectoLabs	< 1.12.8Affected

References

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