Improper cleanup stalls Zebra checkpoint sync via a malicious peer
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
Zebra zebrad before 7.0.0 contains a denial of service flaw in checkpoint sync. A missing cleanup step when a verifier rewind is cancelled after a failed commit lets a malicious peer stall sync. The peer serves a forged block with altered authorizing data plus a restart-triggering block, so the verifier keeps rejecting honest blocks until the node restarts. Exploitation requires only a network connection to a malicious peer.
Written with Claude Haiku 5.5 from the sources below · 2026-11-08
Description from the CNA
Zebra zebrad before 7.0.0 contains a denial of service vulnerability that allows a malicious peer to stall checkpoint sync by cancelling the verifier rewind after a failed commit. Attackers can serve a forged block with altered authorizing data plus a restart-triggering block, leaving the verifier rejecting honest blocks until restart.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| ZcashFoundation | zebra | before 7.0.0 | 7.0.0 | Patch available | CNA |
- zebra VendorZcashFoundation Affected before 7.0.0 Fixed in 7.0.0 Patch available CNA
Remediation
Upgrade ZcashFoundation zebra to version 7.0.0, which fixes the flaw. The sources list no advisory identifier for this fix.
Written with Claude Haiku 5.5 from the sources below · 2026-11-08
- Fix · CNA zebra (ZcashFoundation) Fixed in 7.0.0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
ZcashFoundation zebra 7.0.0
7 records Highest priority Priority MEDIUM 7 MEDIUM
Other records, highest priority first
- TI-2026-86702 Incomplete cleanup in Zebra lets peers stall initial syncPriority MEDIUM 53
- TI-2026-86701 Quadratic signature hashing in Zcash Zebra enables denial of servicePriority MEDIUM 53
- TI-2026-86697 Denial of service in Zebra via unscored script verification failuresPriority MEDIUM 53
Timeline
- 2026-11-08 Threatist record created from CVE-2026-123558
- 2026-11-08 Alias added: GHSA-5hx4-99cr-cchc
References
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-2026-123558 · CVE Program
- CVE-2026-123558 · NVD
- GHSA-5hx4-99cr-cchc · GitHub Advisory Database · CC BY 4.0
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