ZEBRA: Unbounded memory leak in mempool download pipeline via timeout path cancel_handles retention
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-401.
Summary
ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, an unauthenticated P2P peer can cause the mempool download pipeline to retain transactions after verification reaches the outer RATE_LIMIT_DELAY timeout. In zebrad/src/components/mempool/downloads.rs, Downloads::poll_next removed cancel_handles entries after success and ordinary verification errors, but tokio::time::error::Elapsed did not carry the UnminedTxId needed to remove the timed-out entry. Each retained cancel_handles entry could hold a full Gossip::Tx(UnminedTx), while normal mined-transaction cleanup could not match attacker transactions and no periodic garbage collection or count cap existed. Sustained traffic therefore caused monotonic memory growth until swap pressure degraded the node or the operating system terminated the zebrad process for exhausting memory. This issue is fixed in version 4.5.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| ZcashFoundation | zebra | before 4.5.0 | 4.5.0 | Patch available | CNA |
| — | zebrad (crates.io) | before 4.5.0 | 4.5.0 | Patch available | GHSA-65jj-fmw8-468q |
- zebra VendorZcashFoundation Affected before 4.5.0 Fixed in 4.5.0 Patch available CNA
- zebrad (crates.io) Vendor— Affected before 4.5.0 Fixed in 4.5.0 Patch available GHSA-65jj-fmw8-468q
Remediation
- Fix · CNA zebra (ZcashFoundation) Fixed in 4.5.0
- Fix · GHSA-65jj-fmw8-468q zebrad (crates.io) Fixed in 4.5.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-52734
- 2026-10-03 Alias added: GHSA-65jj-fmw8-468q
References
Other 6
- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-65jj-fmw8-468q
- https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557b217a6cd
- https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0
- https://github.com/ZcashFoundation/zebra
- https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebrad/src/components/mempool.rs#L663-L672
- https://github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebrad/src/components/mempool/downloads.rs#L215-L228
More ZcashFoundation vulnerabilities
- TI-2026-66079 Zebra before 4.4.0 Consensus Split via SIGHASH_SINGLE Missing-Output Handling CVSS 4.0HIGH 8.3
- TI-2026-37850 ZEBRA: Mempool transaction admission denial via single-peer inbound queue saturation CVSS 3.1MEDIUM 5.3
- TI-2026-71182 Improper block validation in Zebra gossip lets peers drop new blocks CVSS 4.0MEDIUM 6.3
- TI-2026-29537 Zebra: addr/addrv2 Deserialization Resource Exhaustion CVSS 4.0MEDIUM 6.3
- TI-2026-86702 Incomplete cleanup in Zebra lets peers stall initial sync CVSS 4.0HIGH 8.7
- TI-2026-86701 Quadratic signature hashing in Zcash Zebra enables denial of service CVSS 4.0HIGH 8.7
Sources
- CVE-2026-52734 · CVE Program
- CVE-2026-52734 · NVD
- FIRST EPSS
- GHSA-65jj-fmw8-468q · GitHub Advisory Database · CC BY 4.0
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