CVE-2026-87119 Auth bypass in mpp
Attackers can replay captured subscription keys to repeatedly charge payers and re-authorize server keys due to missing challenge binding in ZenHive mpp.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-87119?
CVE-2026-87119 is a high-severity authentication bypass vulnerability in ZenHive mpp, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.
The payer signs a Tempo KeyAuthorization over the chain id, key type, key id, expiry, limits and scopes only, with nothing tying it to the challenge that prompted it. MPP.Methods.Tempo.KeyAuthorization.verify/3 in lib/mpp/methods/tempo/key_authorization.ex pins each of those signed fields against the subscription request, and the access key it pins is a static per-endpoint server key, so one signed authorization verifies against every challenge the server issues for the same subscription terms. MPP.Methods.Tempo.Subscription.activate/4 deduplicates activations by challenge id, so presenting the captured credential under a fresh challenge produces a different dedup key, claim_activation succeeds, and the subscription transaction is built and broadcast again. Each replay charges the payer's wallet a new first-period settlement and re-authorizes the server key, bounded only by the subscription expiry and the chain's own semantics for re-installing an existing key.
This issue affects mpp: from 0.14.0 before 0.16.2.
Weakness: CWE-294
Which versions are affected by CVE-2026-87119?
1 open source package ship an affected version, including mpp.
| Package | Affected | Fixed in |
|---|---|---|
mpp Hex | From 0.14.0 | 0.16.2 |
How do I fix CVE-2026-87119?
Upgrade mpp to 0.16.2 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-87119 being exploited?
There is no known exploitation of CVE-2026-87119 in the wild and no public exploit code.
Sources
Also known as EEF-CVE-2026-87119, GHSA-h97r-55w6-6rfg, GHSA-p9fv-9w58-95x2.