Read the docs
TI-2026-86701 Aliases CVE-2026-123559GHSA-wgc2-xcwr-9pcw

Quadratic signature hashing in Zcash Zebra enables denial of service

Priority MEDIUM 53CWE-407Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-407.

Summary

Zebra before 7.0.0 from ZcashFoundation contains an inefficient algorithmic complexity flaw (CWE-407). Transaction digest computation grows quadratically with the number of transparent inputs, so transactions with many inputs take excessive time to verify. An unauthenticated remote peer can relay invalid transactions with tens of thousands of inputs, exhausting verification threads and stalling block verification for minutes.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

Description from the CNA

Zebra before 7.0.0 contains an inefficient algorithmic complexity vulnerability that allows unauthenticated peers to exhaust verification threads by submitting transactions with many transparent inputs. Attackers can relay invalid transactions with tens of thousands of inputs, forcing quadratic ZIP-244 or ZIP-243 digest recomputation that stalls Rayon-backed block verification for minutes.

Why it matters now

Fix Fixed zebra (ZcashFoundation): 7.0.0

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
ZcashFoundationzebrabefore 7.0.07.0.0Patch availableCNA
  • zebra VendorZcashFoundation Affected before 7.0.0 Fixed in 7.0.0 Patch available CNA

Remediation

Upgrade the ZcashFoundation zebra product to version 7.0.0, the fixed version listed for it.

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-2026-86700 Improper cleanup stalls Zebra checkpoint sync via a malicious peerPriority MEDIUM 53
    • TI-2026-86697 Denial of service in Zebra via unscored script verification failuresPriority MEDIUM 53
    Show all 7 records →

Timeline

  1. 2026-11-08 Threatist record created from CVE-2026-123559
  2. 2026-11-08 Alias added: GHSA-wgc2-xcwr-9pcw

References

Advisory 1

  • 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-2026-86700 Improper cleanup stalls Zebra checkpoint sync via a malicious peer CVSS 4.0HIGH 8.7
See all 51 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences