CVE-2026-89186
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Exploit Intelligence
Low risk: more likely to be exploited than 33% of all known CVEs.
References
Related Vulnerabilities
Other CWE-524 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2019-9494 | Medium | 5.9 | 3.9% | - | Fix |
| CVE-2021-24027 | High | 7.5 | 3.8% | - | Fix |
| CVE-2019-9495 | Low | 3.7 | 3.5% | - | Fix |
| CVE-2019-14997 | Medium | 4.3 | 1.2% | - | Fix |
| CVE-2024-0874 | Medium | 5.3 | 0.8% | - | Fix |
| CVE-2024-45596 | High | 7.4 | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-89186?
No published fix for CVE-2026-89186 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-89186 being actively exploited?
Not that we know of. CVE-2026-89186 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.39% is the estimated probability that it will be exploited in the next 30 days. That is higher than 33% of all scored CVEs.
How severe is CVE-2026-89186?
CVE-2026-89186 has a CVSS v4 base score of 6.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-16.