CVE-2026-84373

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

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
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 9, 2026

Advisory Details (8)

Auto-updated Sep 1, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v5.0.0-rc.2

Patch available: vitest-dev/vitest v5.0.0-rc.2 (pre-release)

https://github.com/vitest-dev/vitest/releases/tag/v5.0.0-rc.2
github_release Patch Available

v4.1.11

Patch available: vitest-dev/vitest v4.1.11

https://github.com/vitest-dev/vitest/releases/tag/v4.1.11
github_commit Patch Available

commit fe5a11d3ceac (vitest-dev/vitest)

Patch available: vitest-dev/vitest v4.1.11 (contains commit fe5a11d3ceac)

https://github.com/vitest-dev/vitest/commit/fe5a11d3ceac5ec10d6d7d21a46d4caca132c48f
github_commit Patch Available

commit 8ff9b9a9efca (vitest-dev/vitest)

Patch available: vitest-dev/vitest v5.0.0-rc.2 (contains commit 8ff9b9a9efca)

https://github.com/vitest-dev/vitest/commit/8ff9b9a9efca7c6cfd5243569440de8d7a33aec4
github_commit

commit 51edf2b07290 (vitest-dev/vitest)

Fix landed in vitest-dev/vitest commit 51edf2b07290 — awaiting tagged release

https://github.com/vitest-dev/vitest/commit/51edf2b072902aec6d30c90ebaafd8f121c6f9d8
github_pr Patch Available

fix(mocker): restrict redirect mocks to the fs allowlist [backport to v4]

Patch available: vitest-dev/vitest v4.1.11 (PR #10974 merged 2026-08-17)

https://github.com/vitest-dev/vitest/pull/10974
github_pr Patch Available

fix(mocker): restrict redirect mocks to the fs allowlist

Patch available: vitest-dev/vitest v5.0.0-rc.2 (PR #10972 merged 2026-08-17)

https://github.com/vitest-dev/vitest/pull/10972
github Patch Available

Path Traversal / Arbitrary File Read via @vitest/mocker Redirect Mock · Advisory · vitest-dev/vitest · GitHub

https://github.com/vitest-dev/vitest/security/advisories/GHSA-82fw-gwwq-j7x9

Vendor Advisories for CVE-2026-84373(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 1 ecosystem)
npm(2)
PackageVulnerable rangeFixed inDependents
vitest—5.0.0-rc.2—
@vitest/mocker—5.0.0-rc.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-09-16 09:32 UTCEG score recompute
  2. 2026-09-16 05:15 UTCEPSS rescore
  3. 2026-09-15 07:28 UTCEG score recompute
  4. 2026-09-15 03:12 UTCEPSS rescore
  5. 2026-09-15 03:12 UTCEPSS rescore
  6. 2026-09-14 05:25 UTCEG score recompute
  7. 2026-09-13 03:22 UTCEG score recompute
  8. 2026-09-12 01:18 UTCEG score recompute
  9. 2026-09-11 14:53 UTCEPSS rescore
  10. 2026-09-11 14:53 UTCEPSS rescore
  11. 2026-09-10 23:14 UTCEG score recompute
  12. 2026-09-09 02:59 UTCEG score recompute
  13. 2026-09-08 22:01 UTCEPSS rescore
  14. 2026-09-08 00:55 UTCEG score recompute
  15. 2026-09-06 22:51 UTCEG score recompute
  16. 2026-09-06 13:48 UTCEPSS rescore
  17. 2026-09-05 20:46 UTCEG score recompute
  18. 2026-09-05 15:31 UTCEPSS rescore
  19. 2026-09-04 18:43 UTCEG score recompute
  20. 2026-09-04 05:07 UTCEPSS rescore
  21. 2026-09-02 14:29 UTCEG score recompute
  22. 2026-09-02 14:12 UTCEPSS rescore
  23. 2026-09-02 13:34 UTCEG score recompute
  24. 2026-09-01 22:19 UTCEG score recompute
  25. 2026-09-01 21:33 UTCEG score recompute
Show 1 more
  1. 2026-09-01 21:32 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-84373?
CVE-2026-84373 is a medium vulnerability published on September 1, 2026. 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…
When was CVE-2026-84373 disclosed?
CVE-2026-84373 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84373 actively exploited?
CVE-2026-84373 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 69.0% of all scored CVEs.
What is the CVSS score of CVE-2026-84373?
CVE-2026-84373 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-84373?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84373, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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