CVE-2026-89186
mpp writes Payment-Receipt and Cache-Control before the wrapped application runs, letting a consumer's own Cache-Control expose paid responses to shared caches
- State
- Published
- Severity
- 6.3 Medium
- Published
- Sep 16, 2026
- Updated
- Sep 16, 2026
- Reserved
- Sep 11, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.3 Medium | 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 | EEF |
Weaknesses
- CWE-524 Use of Cache Containing Sensitive Information
Affected Products
| Product | Versions |
|---|---|
mppZenHive |
|
mppZenHive |
|
References
- GitHub Advisoryrelatedvendor-advisory
- EEF CNA record for CVE-2026-89186related
- OSV record EEF-CVE-2026-89186related
- Introducing commit 2d4d1d9 in ZenHive/mpprelated
- Fix commit 2fd91a5 in ZenHive/mpppatch
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