{"id":"CVE-2026-52732","summary":"ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation","details":"ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, one unauthenticated P2P peer can monopolize all 25 MAX_INBOUND_CONCURRENCY slots in Zebra's inbound mempool download and verification pipeline. In zebrad/src/components/mempool/downloads.rs, the bounded queue was shared globally without per-peer accounting, while peer identity was not carried through Gossip and FullQueue responses were mapped to Response::Nil instead of reaching overload disconnection handling. An attacker can advertise fake transaction identifiers and remain silent so each task holds a slot until TRANSACTION_DOWNLOAD_TIMEOUT, then periodically refill the queue as slots expire. While saturated, honest peer transactions and local sendrawtransaction requests are rejected with MempoolError::FullQueue, although block validation and synchronization continue. This issue is fixed in version 4.5.0.","aliases":["GHSA-4fc2-h7jh-287c"],"modified":"2026-08-20T03:54:30.343713882Z","published":"2026-08-18T19:26:07.345Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52732.json"},"references":[{"type":"WEB","url":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52732.json"},{"type":"ADVISORY","url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52732"},{"type":"FIX","url":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zcashfoundation/zebra","events":[{"introduced":"0"},{"fixed":"1440b43ca7df59aca948090d45117557b217a6cd"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"4.5.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v4.4.0","v4.4.1","v4.3.1","4.3.1","v4.3.0","v4.2.0","v4.1.0","v4.0.0","v3.1.0","v3.0.0","v3.0.0-rc.0","v2.5.0","v2.0.1","v2.4.2","v2.3.0","v2.4.0","v2.0.0","v2.2.0","v2.1.0","v2.0.0-rc.0","v1.9.0","v1.8.0","v1.7.0","v1.6.1","v1.6.0","v1.5.2","v1.5.1","v1.5.0","v1.4.0","v1.3.0","v1.2.0","v1.1.0","v1.0.1","v1.0.0","v1.0.0-rc.9","v1.0.0-rc.8","v1.0.0-rc.7","v1.0.0-rc.6","v1.0.0-rc.5","v1.0.0-rc.0","v1.0.0-rc.4","v1.0.0-rc.3","v1.0.0-rc.2","v1.0.0-rc.1","v1.0.0-beta.15","v1.0.0-beta.14","v1.0.0-beta.13","v1.0.0-beta.12","v1.0.0-beta.11","v1.0.0-beta.10","v1.0.0-beta.9","v1.0.0-beta.8","v1.0.0-beta.7","v1.0.0-beta.6","v1.0.0-beta.5","v1.0.0-beta.4","v1.0.0-beta.3","v1.0.0-beta.2","v1.0.0-beta.1","v1.0.0-beta.0","v1.0.0-alpha.19","v1.0.0-alpha.18","v1.0.0-alpha.17","v1.0.0-alpha.16","v1.0.0-alpha.15","v1.0.0-alpha.14","v1.0.0-alpha.13","v1.0.0-alpha.12","v1.0.0-alpha.11","v1.0.0-alpha.10","v1.0.0-alpha.9","v1.0.0-alpha.8","v1.0.0-alpha.7","v1.0.0-alpha.6","v1.0.0-alpha.5","v1.0.0-alpha.4","v1.0.0-alpha.3","v1.0.0-alpha.2","v1.0.0-alpha.1","v1.0.0-alpha.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52732.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}