{"answers":{"affected":"1 open source package ship an affected version, including mpp.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-89420 exists.","fix":"Upgrade mpp to 0.16.2 or later.","what":"CVE-2026-89420 is a high-severity vulnerability in ZenHive mpp, published on 22 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-89420 and fix it if it is affected.\n\nWhat it is: CVE-2026-89420 is a high-severity vulnerability in ZenHive mpp, published on 22 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-89420 exists.\n\nAffected packages and fixed versions:\n- mpp (Hex): affected from 0.14.0; fixed in 0.16.2\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-89420/ (Markdown: https://insights.sbomify.com/CVE-2026-89420/index.md)","id":"CVE-2026-89420","markdown":"https://insights.sbomify.com/CVE-2026-89420/index.md","name":"CVE-2026-89420","record":{"aliases":["EEF-CVE-2026-89420","GHSA-8c63-r789-xrrf","GHSA-96m7-5wfv-978m"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_read","security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"Elixir payment library","requires_auth":"low_privilege","summary":"Attackers can access paid resources for free by replaying session vouchers, bypassing payment validation in the ZenHive mpp library.","user_interaction":"not_required","vuln_class":"business_logic"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"EEF","cpe":[],"cvss":{"score":7.1,"severity":"high","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-1284","name":"Improper Validation of Specified Quantity in Input"}],"description":"Improper Validation of Specified Quantity in Input in ZenHive mpp allows a client holding an open payment channel to obtain paid resources without being charged.\n\nMPP.Session.Actions.accept_voucher/3 in lib/mpp/session/actions.ex treats a voucher whose cumulativeAmount equals the channel's already-accepted cumulative amount as an idempotent success, returning the channel unchanged without calling maybe_spend/2. The credential verifies, the protected resource is served, and spent and units stay where they were. Because the server issues a fresh challenge per request and the credential replay store keys on challenge id and payload, the same signed voucher can be re-presented under every new challenge, so one paid voucher yields an unbounded number of paid units. The path is reachable from any method built on MPP.Session.Method through the Plug, MCP, JSON-RPC and WebSocket transports.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2.","ecosystems":["Hex"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"Session voucher adding no new funds is accepted without a charge in mpp, serving paid resources for free","id":"CVE-2026-89420","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Hex","product":null,"products":[],"type":"business_logic","year":"2026"},"n_packages":1,"n_references":5,"next":{"headline":"TLS 1.3 client skips server authentication when ServerHello carries an unsolicited pre_shared_key extension","id":"CVE-2026-89422"},"packages":[{"ecosystem":"Hex","fixed":["0.16.2"],"introduced":["0.14.0"],"last_affected":[],"package":"mpp","purl":"pkg:hex/mpp","source":"EEF-CVE-2026-89420"}],"prev":{"headline":"OpenStack Ironic before 39.0.1 sometimes allows a user to change the maintenance setting on a node via PATCH to /v1/nodes/{ident} - in other","id":"CVE-2026-89419"},"products":["mpp"],"published":"2026-09-22","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"Erlang Ecosystem Foundation","prefix":"EEF"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-22","vendors":["ZenHive"]},"summary":"Attackers can access paid resources for free by replaying session vouchers, bypassing payment validation in the ZenHive mpp library.","url":"https://insights.sbomify.com/CVE-2026-89420/"}