November 14, 2026

CVE Watchtower

CVE-2026-109363ZcashFoundation zebra

NVD

Vulnerability Summary

ZcashFoundation Zebra 6.4.0 before 6.4.2 parses version 6 transactions carrying a pre-NU6.3 consensus branch ID, but the size computation during UnminedTx construction treats re-serialization of the Orchard bundle as infallible, so the resulting error trips an expect that aborts zebrad. Unauthenticated peers can send a single pre-handshake tx message to crash the node, and can repeat this after each restart.
Severity Level
HIGH(8.7)
Published Date
Oct 12, 2026
Last Modified
Oct 13, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.43%Probability
Root Weakness (CWE)
CWE-617 ↗
See the MITRE CWE entry for the full definition of this weakness.
CVSS v4.0 Base Metrics — Score 8.7 (HIGH)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Attack VectorNetwork
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)None
Integrity (Vulnerable System)None
Availability (Vulnerable System)High
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 7.5)
CVSS v3.1 Base Metrics — Score 7.5 (HIGH)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh

Affected & Patched Versions

Affected Versions
  • ZcashFoundation zebra >= 6.4.0 and < 6.4.2
Patched Versions
  • ZcashFoundation zebra 6.4.2

What to do

Plan remediation soon. No exploitation is confirmed yet, but the severity is high.

  1. Check whether you run ZcashFoundation zebra and which version.
  2. Update to a patched version listed above, then confirm the new version.

Timeline

  • Oct 12, 2026Published
  • Oct 13, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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External References

Data last checked: Nov 14, 2026 03:11 UTC