Hoverfly: Process Crash via Concurrent Map Write Race Condition in Diff Mode (CVE-2026-50013) | HOL Guard CVE

High severityCVE-2026-50013GHSA-QRH4-P6V4-MRFG

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

Answer in brief

CVE-2026-50013 records a High severity vulnerability in Hoverfly: Process Crash via Concurrent Map Write Race Condition in Diff Mode. The current sources do not mark it as known exploited. The current feed maps SpectoLabs/hoverfly (generic), github.com/SpectoLabs/hoverfly (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 14, 2026Source checked Sep 17, 2026First seen by HOL Jul 15, 2026Material review Sep 14, 2026

Upstream Advisory

Key facts

Risk: High
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps SpectoLabs/hoverfly (generic), github.com/SpectoLabs/hoverfly (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
SpectoLabs/hoverflygeneric	< 1.12.8	Not reported
github.com/SpectoLabs/hoverflygo	<=1.12.7	1.12.8

Recommended response

Check inventory. Check lockfiles and deployed manifests for SpectoLabs/hoverfly, github.com/SpectoLabs/hoverfly.
Review the reported fix. Update github.com/SpectoLabs/hoverfly to 1.12.8 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 15, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.