{"id":"CVE-2026-87119","state":"PUBLISHED","title":"mpp Tempo subscription key authorization is not bound to the issuing challenge, allowing a captured activation credential to be replayed","description":"Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.\n\nThe 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.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2.","publishedAt":"2026-09-22T11:16:56.232Z","updatedAt":"2026-09-22T12:02:31.484Z","severity":{"score":8.2,"label":"High","version":"4.0","vector":"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","source":"EEF"},"assigner":"EEF","products":["ZenHive mpp"],"affected":[{"vendor":"ZenHive","product":"mpp","packageName":"mpp","packageURL":"pkg:hex/mpp","defaultStatus":"unaffected","versions":[{"version":"0.14.0","status":"affected","lessThan":"0.16.2","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Methods.Tempo.KeyAuthorization'","'Elixir.MPP.Methods.Tempo.Subscription'"],"programFiles":["lib/mpp/methods/tempo/key_authorization.ex","lib/mpp/methods/tempo/subscription.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':verify/3"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':wallet_params/2"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':from_rpc/1"},{"name":"'Elixir.MPP.Methods.Tempo.Subscription':verify/2"}],"repo":"https://github.com/ZenHive/mpp"},{"vendor":"ZenHive","product":"mpp","packageName":"zenhive/mpp","packageURL":"pkg:github/zenhive/mpp","defaultStatus":"unaffected","versions":[{"version":"db464dfa9a86ccda58f0827101f6da6bd8aafa78","status":"affected","lessThan":"4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Methods.Tempo.KeyAuthorization'","'Elixir.MPP.Methods.Tempo.Subscription'"],"programFiles":["lib/mpp/methods/tempo/key_authorization.ex","lib/mpp/methods/tempo/subscription.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':verify/3"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':wallet_params/2"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':from_rpc/1"},{"name":"'Elixir.MPP.Methods.Tempo.Subscription':verify/2"}],"repo":"https://github.com/ZenHive/mpp"}],"references":["https://github.com/ZenHive/mpp/security/advisories/GHSA-p9fv-9w58-95x2","https://cna.erlef.org/cves/CVE-2026-87119.html","https://osv.dev/vulnerability/EEF-CVE-2026-87119","https://github.com/ZenHive/mpp/commit/db464dfa9a86ccda58f0827101f6da6bd8aafa78","https://github.com/ZenHive/mpp/commit/4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f"],"weaknesses":["CWE-294"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/87xxx/CVE-2026-87119.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-87119","state":"PUBLISHED","datePublished":"2026-09-22T11:16:56.232Z","dateUpdated":"2026-09-22T12:02:31.484Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-09-11T18:00:02.032Z"},"containers":{"cna":{"title":"mpp Tempo subscription key authorization is not bound to the issuing challenge, allowing a captured activation credential to be replayed","descriptions":[{"lang":"en","value":"Authentication Bypass by Capture-replay in ZenHive mpp allows an attacker holding a captured subscription activation credential to charge the payer repeatedly.\n\nThe 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.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2."}],"affected":[{"vendor":"ZenHive","product":"mpp","packageName":"mpp","packageURL":"pkg:hex/mpp","defaultStatus":"unaffected","versions":[{"version":"0.14.0","status":"affected","lessThan":"0.16.2","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Methods.Tempo.KeyAuthorization'","'Elixir.MPP.Methods.Tempo.Subscription'"],"programFiles":["lib/mpp/methods/tempo/key_authorization.ex","lib/mpp/methods/tempo/subscription.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':verify/3"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':wallet_params/2"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':from_rpc/1"},{"name":"'Elixir.MPP.Methods.Tempo.Subscription':verify/2"}],"repo":"https://github.com/ZenHive/mpp"},{"vendor":"ZenHive","product":"mpp","packageName":"zenhive/mpp","packageURL":"pkg:github/zenhive/mpp","defaultStatus":"unaffected","versions":[{"version":"db464dfa9a86ccda58f0827101f6da6bd8aafa78","status":"affected","lessThan":"4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*"],"modules":["'Elixir.MPP.Methods.Tempo.KeyAuthorization'","'Elixir.MPP.Methods.Tempo.Subscription'"],"programFiles":["lib/mpp/methods/tempo/key_authorization.ex","lib/mpp/methods/tempo/subscription.ex"],"programRoutines":[{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':verify/3"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':wallet_params/2"},{"name":"'Elixir.MPP.Methods.Tempo.KeyAuthorization':from_rpc/1"},{"name":"'Elixir.MPP.Methods.Tempo.Subscription':verify/2"}],"repo":"https://github.com/ZenHive/mpp"}],"references":[{"url":"https://github.com/ZenHive/mpp/security/advisories/GHSA-p9fv-9w58-95x2","name":"GitHub Advisory","tags":["related","vendor-advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-87119.html","name":"EEF CNA record for CVE-2026-87119","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-87119","name":"OSV record EEF-CVE-2026-87119","tags":["related"]},{"url":"https://github.com/ZenHive/mpp/commit/db464dfa9a86ccda58f0827101f6da6bd8aafa78","name":"Introducing commit db464df in ZenHive/mpp","tags":["related"]},{"url":"https://github.com/ZenHive/mpp/commit/4b6eaec02af0e8485cfb4ff68f467d075ed5dd6f","name":"Fix commit 4b6eaec in ZenHive/mpp","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"HIGH","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.2,"baseSeverity":"HIGH","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-294","description":"CWE-294 Authentication Bypass by Capture-replay","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-09-22T11:16:56.232Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Only deployments offering Tempo subscriptions are affected, which requires <code>subscription_access_key_private_key</code> in the Tempo <code>method_config</code>. Exploitation further requires the attacker to have obtained a payer's signed activation credential, in transit over a hop that is not TLS-protected or at rest in a log, an intermediary, or a client retry buffer.</p>"},{"base64":false,"type":"text/markdown","value":"Only deployments offering Tempo subscriptions are affected, which requires `subscription_access_key_private_key` in the Tempo `method_config`. Exploitation further requires the attacker to have obtained a payer's signed activation credential, in transit over a hop that is not TLS-protected or at rest in a log, an intermediary, or a client retry buffer."}],"value":"Only deployments offering Tempo subscriptions are affected, which requires subscription_access_key_private_key in the Tempo method_config. Exploitation further requires the attacker to have obtained a payer's signed activation credential, in transit over a hop that is not TLS-protected or at rest in a log, an intermediary, or a client retry buffer."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ZenHive:mpp:*:*:*:*:*:*:*:*","versionEndExcluding":"0.16.2","versionStartIncluding":"0.14.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"E.FU"},{"lang":"en","type":"remediation developer","value":"E.FU"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"dateAssigned":"2026-09-15T15:20:31.000Z","impacts":[{"capecId":"CAPEC-60","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>An attacker who obtains a payer's subscription activation credential (from a non-TLS hop, a log, a compromised intermediary, or the client's own retry buffer) can present it under fresh challenges to settle repeated first-period charges against that payer's wallet and re-authorize the server's access key. The payer bears the on-chain cost, limited only by the per-period subscription limit and the subscription expiry.</p>"},{"base64":false,"type":"text/markdown","value":"An attacker who obtains a payer's subscription activation credential (from a non-TLS hop, a log, a compromised intermediary, or the client's own retry buffer) can present it under fresh challenges to settle repeated first-period charges against that payer's wallet and re-authorize the server's access key. The payer bears the on-chain cost, limited only by the per-period subscription limit and the subscription expiry."}],"value":"An attacker who obtains a payer's subscription activation credential (from a non-TLS hop, a log, a compromised intermediary, or the client's own retry buffer) can present it under fresh challenges to settle repeated first-period charges against that payer's wallet and re-authorize the server's access key. The payer bears the on-chain cost, limited only by the per-period subscription limit and the subscription expiry."}]}],"source":{"discovery":"INTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-22T12:02:12.184296Z","id":"CVE-2026-87119","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-22T12:02:31.484Z"}}]}}}