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Fencer Intel
high 8.2

CVE-2026-87119 json

mpp Tempo subscription key authorization is not bound to the issuing challenge, allowing a captured activation credential to be replayed

published 2mo ago modified last mo. also EEF-CVE-2026-87119 , EUVD-2026-84361 , GHSA-p9fv-9w58-95x2

cvss
8.2
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 47%
public exploits
0
none known

Summary

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.

Patch / fix

  • hex mpp 0.16.2
  • ZenHive mpp 0.16.2

Is CVE-2026-87119 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.57% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/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

Affected packages

ecosystem package affected fixed in
hex mpp
>=0.14.0, <0.16.2
0.16.2

Affected products

  • ZenHive mpp

Classification

Weakness
  • CWE-294 Authentication Bypass by Capture-replay

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of ZenHive/mpp published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.