Threadlinqs IntelligenceStart free

VulnerabilityCVE-2026-84373Published 2026-09-01

CVE-2026-84373 — vitest-dev vitest

medium

As of 2026-09-02, CVE-2026-84373 is a MEDIUM-severity vulnerability in vitest-dev vitest, CVSS v3.1 5.9, EPSS 0.3% (30.5th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-84373 as of 2026-09-02; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v3.1
5.9/10Medium
EPSS
0.3%Higher than 30.5% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
0None linked yet
Priority
4.2/10Threadlinqs triage score
Published
Updated 2026-09-02
CVSS v3.1 5.9 (MEDIUM) · EPSS 0.3% (higher than 30.5% of all scored CVEs) · Priority 4.2/10 · Published 2026-09-01

Last updated:

What is CVE-2026-84373?

Vitest is a testing framework powered by Vite. From 2.1.0 until 4.1.11 and 5.0.0-rc.2, the public mockerPlugin and standalone interceptorPlugin exports in packages/mocker/src/node/interceptorPlugin.ts register the vitest:interceptor:register handler on Vite's unauthenticated HMR WebSocket without validating redirect targets against the file-serving allowlist. The implementation processes event.redirect without enforcing server.fs.allow and server.fs.deny through isFileLoadingAllowed. A remote client that can reach an exposed development server can submit an opaque URL scheme preserving .. segments, causing join(server.config.root, redirectUrl.pathname) to resolve outside the project root. The plugin's load hook then returns readFile(mock.redirect, 'utf-8') as module source, disclosing local files readable by the dev-server process. Vitest browser mode uses a token-authenticated RPC and is not remotely unauthenticated by default, although the same boundary check was missing on that path. This issue is fixed in versions 4.1.11 and 5.0.0-rc.2.

The record classifies CVE-2026-84373 under weakness class CWE-22. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 2 affected-product entries are recorded, across 2 vendors, listed below. The identifier was first published 34 days ago.

Severity and exploitation probability

CVSS v3.1 base score
5.9 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS (FIRST)
0.3% probability of exploitation in the next 30 days, higher than 30.5% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
4.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-09-01, last modified 2026-09-02

Is CVE-2026-84373 being exploited?

It currently carries a trending score of 37 in the Threadlinqs vulnerability feed.

Affected products and versions

  • vitest-dev: vitest
  • @vitest: mocker

How to fix CVE-2026-84373

No vendor patch reference has been recorded for CVE-2026-84373 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-84373

No threat campaign in the Threadlinqs corpus currently references CVE-2026-84373, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch

Other references

Showing 6 of 8 recorded references.