CVE-2026-52732: medium-severity vulnerability in ZcashFoundation zebra
ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation
Published
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13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
ZcashFoundation · zebraRelated CVEs — ZcashFoundation zebra
In the same product, most dangerous first.
CVE-2026-34202CRITICALZebra node crash — V5 transaction hash panic (P2P reachable)EPSS 0.8%CVE-2026-52736HIGHZEBRA: Block suppression via NU5 same-header body poisoning of sent-hash cacheEPSS 0.6%CVE-2026-52829HIGHZEBRA: IPv4-Mapped Mempool Misbehavior Update Aborts Zebra Address BookEPSS 0.6%CVE-2026-52731MEDIUMZEBRA: Full node denial of service via non-ASCII LongPollId in getblocktemplateEPSS 0.5%CVE-2026-52739MEDIUMZEBRA: Repeated Non-Finalized Shielded Transaction Aborts Zebra Before Duplicate-Nullifier RejectionEPSS 0.5%CVE-2026-52738MEDIUMZEBRA: Finalized address balance credit-first overflow on consensus-valid blocksEPSS 0.5%