CVE-2026-89186

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% 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
Trending — 4 sources updated this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.3Exploit: None knownExposed: 0

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

Use of Cache Containing Sensitive Information in ZenHive mpp allows a shared HTTP cache to store a paid response and serve it to clients that never paid.

MPP.Plug.verify_credential in lib/mpp/plug.ex sets payment-receipt and cache-control: private on the connection before the wrapped application runs, and registers no register_before_send/2 callback. Plug.Conn.put_resp_header/3 replaces an existing header, so a mounting application that sets its own cache-control on the paid resource (for example public, max-age=3600) silently overrides the private the library relies on, and a CDN or reverse proxy can then store the paid 200 together with its Payment-Receipt and serve both to unpaid clients. The library-level guarantee is therefore defeatable by the application it protects. For the same reason a downstream non-2xx response still carried Payment-Receipt, issuing a receipt for a response that delivered no resource.

This issue affects mpp: from 0.1.0 before 0.16.2.

CVSS v3
6.3
EG Score
6.3(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity63% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

Advisory Details (5)

Auto-updated Sep 16, 2026
Patch available. Sources: github_commit, github.
github_commit

commit 2fd91a5ecbd0 (ZenHive/mpp)

Fix landed in ZenHive/mpp commit 2fd91a5ecbd0 — awaiting tagged release

https://github.com/ZenHive/mpp/commit/2fd91a5ecbd0b0ad2a4ac202b79659e8126dbc0b
github_commit

commit 2d4d1d94aae7 (ZenHive/mpp)

Fix landed in ZenHive/mpp commit 2d4d1d94aae7 — awaiting tagged release

https://github.com/ZenHive/mpp/commit/2d4d1d94aae7790ae0623063961adbeef171fa71
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-89186
generic

CVE-2026-89186

https://cna.erlef.org/cves/CVE-2026-89186.html
github Patch Available

Payment-Receipt and Cache-Control: private written before the downstream app runs — consumer Cache-Control can expose paid responses to shared caches · Advisory · ZenHive/mpp · GitHub

https://github.com/ZenHive/mpp/security/advisories/GHSA-82qh-vrvm-gqvc

Vendor Advisories for CVE-2026-89186(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 15× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 18:43 UTCGHSA enrichment
  3. 2026-09-17 19:53 UTCEG score recompute
  4. 2026-09-17 19:53 UTCGHSA enrichment
  5. 2026-09-17 19:32 UTCEPSS rescore
  6. 2026-09-16 21:01 UTCGHSA enrichment
  7. 2026-09-16 15:25 UTCEG score recompute
  8. 2026-09-16 15:25 UTCGHSA enrichment
  9. 2026-09-16 15:01 UTCEG score recompute
  10. 2026-09-16 15:01 UTCGHSA enrichment
  11. 2026-09-16 14:09 UTCEPSS rescore
  12. 2026-09-16 09:31 UTCEG score recompute
  13. 2026-09-16 09:31 UTCGHSA enrichment
  14. 2026-09-16 08:27 UTCEG score recompute
  15. 2026-09-16 08:26 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-89186?
CVE-2026-89186 is a medium vulnerability published on September 16, 2026. Use of Cache Containing Sensitive Information in ZenHive mpp allows a shared HTTP cache to store a paid response and serve it to clients that never paid. MPP.Plug.verifycredential in lib/mpp/plug.ex sets payment-receipt and cache-control: private on the connection before the wrapped application…
When was CVE-2026-89186 disclosed?
CVE-2026-89186 was first published in the National Vulnerability Database on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89186 actively exploited?
CVE-2026-89186 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 66.6% of all scored CVEs.
What is the CVSS score of CVE-2026-89186?
CVE-2026-89186 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-89186?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-89186, 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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