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.
CVE-2026-50013
“—” beside the score: it is equal to the CVSS score beside it.
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (38th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 49EG Risk 49/100
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computed (value × EchelonGraph’s weight)Severity75% × 45%The EG Score, 7.5 of 10.Exploitation0.5% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.5%
- EPSS %ILE
- 38th
- KEV
- Not listed
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
July 14, 2026
Last Modified
September 30, 2026
Advisory Details (3)
Auto-updated Sep 11, 2026v1.12.8
Patch available: SpectoLabs/hoverfly v1.12.8
https://github.com/SpectoLabs/hoverfly/releases/tag/v1.12.8fix: race in Diff mode crashes Hoverfly (GHSA-qrh4-p6v4-mrfg)
Fix merged in SpectoLabs/hoverfly PR #1227 on 2026-05-27 — awaiting tagged release
https://github.com/SpectoLabs/hoverfly/pull/1227Process Crash via Concurrent Map Write Race Condition in Diff Mode · Advisory · SpectoLabs/hoverfly · GitHub
https://github.com/SpectoLabs/hoverfly/security/advisories/GHSA-qrh4-p6v4-mrfgVendor Advisories for CVE-2026-50013(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
Go(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| github.com/SpectoLabs/hoverfly | — |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 11× in last 7d / 34× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-12 15:59 UTCEG score recompute
- 2026-10-11 19:42 UTCEG score recompute
- 2026-10-11 16:57 UTCEG score recompute
- 2026-10-11 14:21 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-30 20:04 UTCEG score recompute
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-28 08:57 UTCEG score recompute
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-09-24 09:02 UTCEG score recompute
Show 17 moreShow fewer
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-23 03:33 UTCEG score recompute
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-18 04:52 UTCEG score recompute
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-14 19:23 UTCEG score recompute
- 2026-09-14 18:28 UTCEG score recompute
- 2026-09-13 23:16 UTCEG score recompute
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-13 07:40 UTCEG score recompute
- 2026-09-11 23:11 UTCEG score recompute
- 2026-07-30 09:52 UTCEG score recompute
- 2026-07-26 11:43 UTCEG score recompute
- 2026-07-23 03:18 UTCEG score recompute
- 2026-07-14 18:10 UTCEG score recompute
Related CVEs(same product + same CWE)
Same product
4 shownGo:github.com/SpectoLabs/hoverfly
Frequently asked(5)
What is CVE-2026-50013?
When was the CVE record for CVE-2026-50013 published?
Is CVE-2026-50013 actively exploited?
What is the CVSS score of CVE-2026-50013?
How do I remediate CVE-2026-50013?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-50013
Is Your Infrastructure Affected by CVE-2026-50013?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.