Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and zebra-consensus version 5.0.2, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By carefully submitting a transaction that is valid for height H+1 but invalid for H+2 and then mining that transaction in a block at height H+2, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This vulnerability is fixed in zebrad version 4.3.1 and zebra-consensus version 5.0.2.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- 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 | zebrad | before 4.3.1 | 4.3.1 | Patch available | CNA |
| ZcashFoundation | zebra-consensus | before 5.0.2 | 5.0.2 | Patch available | CNA |
| — | zebra-consensus (crates.io) | before 5.0.2 | 5.0.2 | Patch available | GHSA-xvj8-ph7x-65gf |
| — | zebrad (crates.io) | before 4.3.1 | 4.3.1 | Patch available | GHSA-xvj8-ph7x-65gf |
- zebrad VendorZcashFoundation Affected before 4.3.1 Fixed in 4.3.1 Patch available CNA
- zebra-consensus VendorZcashFoundation Affected before 5.0.2 Fixed in 5.0.2 Patch available CNA
- zebra-consensus (crates.io) Vendor— Affected before 5.0.2 Fixed in 5.0.2 Patch available GHSA-xvj8-ph7x-65gf
- zebrad (crates.io) Vendor— Affected before 4.3.1 Fixed in 4.3.1 Patch available GHSA-xvj8-ph7x-65gf
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:zfnd:zebra-consensus:*:*:*:*:*:rust:*:* | before 5.0.2 | Vulnerable | ZcashFoundation |
| cpe:2.3:a:zfnd:zebrad:*:*:*:*:*:rust:*:* | before 4.3.1 | Vulnerable | ZcashFoundation |
- cpe:2.3:a:zfnd:zebra-consensus:*:*:*:*:*:rust:*:* Versions before 5.0.2 Vulnerable ·ZcashFoundation
- cpe:2.3:a:zfnd:zebrad:*:*:*:*:*:rust:*:* Versions before 4.3.1 Vulnerable ·ZcashFoundation
Remediation
- Fix · CNA zebrad (ZcashFoundation) Fixed in 4.3.1
- Fix · CNA zebra-consensus (ZcashFoundation) Fixed in 5.0.2
- Fix · GHSA-xvj8-ph7x-65gf zebra-consensus (crates.io) Fixed in 5.0.2 Advisory →
- Fix · GHSA-xvj8-ph7x-65gf zebrad (crates.io) Fixed in 4.3.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-40880
- 2026-10-03 Alias added: GHSA-xvj8-ph7x-65gf
References
More ZcashFoundation Zebra-consensus vulnerabilities
- TI-2026-26663 Zebra has a Consensus Failure due to Improper Verification of V5 Transactions CVSS 4.0HIGH 8.4
Sources
- CVE-2026-40880 · CVE Program
- CVE-2026-40880 · NVD
- FIRST EPSS
- GHSA-xvj8-ph7x-65gf · GitHub Advisory Database · CC BY 4.0
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