High 7.5Published Sep 11, 2026

CVE-2026-50013Hoverfly: Process Crash via Concurrent Map Write Race Condition in Diff Mode

Updated under an hour ago (2026-10-19 08:30 UTC)

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It affects SpectoLabs hoverfly. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for SpectoLabs hoverfly

Exploited in the last 30 days

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: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-362, CWE-820
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Sep 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

SpectoLabs hoverfly spectolabs:hoverfly (from the name)	before 1.12.8	CNA record

References

https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-qrh4-p6v4-mrfgx-refsource-confirm
https://github.com/SpectoLabs/hoverfly/pull/1227x-refsource-misc
https://github.com/SpectoLabs/hoverfly/releases/tag/v1.12.8x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.