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TI-2026-36839 Aliases CVE-2026-50013GHSA-qrh4-p6v4-mrfg

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

Priority LOW 39CWE-362Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0047 40th percentileScored 2026-11-07
Fix Fixed hoverfly (SpectoLabs): 1.12.8github.com/SpectoLabs/hoverfly (Go): 1.12.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
SpectoLabshoverflybefore 1.12.81.12.8Patch availableCNA
—github.com/SpectoLabs/hoverfly (Go)before 1.12.81.12.8Patch availableGHSA-qrh4-p6v4-mrfg
  • hoverfly VendorSpectoLabs Affected before 1.12.8 Fixed in 1.12.8 Patch available CNA
  • github.com/SpectoLabs/hoverfly (Go) Vendor— Affected before 1.12.8 Fixed in 1.12.8 Patch available GHSA-qrh4-p6v4-mrfg

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:hoverfly:hoverfly:*:*:*:*:*:*:*:*——SpectoLabs
  • cpe:2.3:a:hoverfly:hoverfly:*:*:*:*:*:*:*:* Versions — — ·SpectoLabs

Remediation

  • Fix · CNA hoverfly (SpectoLabs) Fixed in 1.12.8
  • Fix · GHSA-qrh4-p6v4-mrfg github.com/SpectoLabs/hoverfly (Go) Fixed in 1.12.8 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-50013
  2. 2026-10-03 Alias added: GHSA-qrh4-p6v4-mrfg

References

Other 4

  • TI-2025-33966 Improper input validation in SpectoLabs hoverfly CVSS 3.1CRITICAL 9.8
  • TI-2025-34185 Hoverfly's WebSocket endpoint `/api/v2/ws/logs` reachable without authentication even when --auth is enabled. CVSS 4.0HIGH 7.8
  • TI-2024-30437 Arbitrary file read in the `/api/v2/simulation` endpoint in hoverfly (`GHSL-2023-274`) CVSS 3.1HIGH 7.5
  • TI-2026-36844 Hoverfly: Denial of Service via Goroutine Leak in Remote Post-Serve Actions CVSS 3.1MEDIUM 6.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences