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Vulnerability record · CVE-2026-50013 · published 11 September 2026

CVE-2026-50013: Race condition vulnerability

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.

7.5 CVSS 3.1 High EPSS 0.47% · top 61.8% CWE-362 · Race conditionCWE-820 · CWE-820 Received
7.5CVSS 3.1 base score
0.47%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
14 Sep 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

LinkTags
https://github.com/SpectoLabs/hoverfly/pull/1227
https://github.com/SpectoLabs/hoverfly/releases/tag/v1.12.8
https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-qrh4-p6v4-mrfg

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Source: NIST National Vulnerability Database (record CVE-2026-50013), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.