{"id":"CVE-2026-52732","state":"PUBLISHED","title":"ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation","description":"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.","publishedAt":"2026-08-18T19:26:07.345Z","updatedAt":"2026-08-18T19:32:31.103Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["ZcashFoundation zebra"],"affected":[{"vendor":"ZcashFoundation","product":"zebra","versions":[{"version":"< 4.5.0","status":"affected"}]}],"references":["https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c","https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/52xxx/CVE-2026-52732.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52732","state":"PUBLISHED","datePublished":"2026-08-18T19:26:07.345Z","dateUpdated":"2026-08-18T19:32:31.103Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-08T14:00:43.572Z"},"containers":{"cna":{"title":"ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"ZcashFoundation","product":"zebra","versions":[{"version":"< 4.5.0","status":"affected"}]}],"references":[{"url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c","name":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","name":"https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd","tags":["x_refsource_MISC"]},{"url":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","name":"https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-18T19:26:07.345Z"},"source":{"advisory":"GHSA-4fc2-h7jh-287c","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4fc2-h7jh-287c","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-18T19:32:12.651849Z","id":"CVE-2026-52732","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-18T19:32:31.103Z"}}]}}}