November 14, 2026

CVE Watchtower

CVE-2026-123555ZcashFoundation zebra

NVD

Vulnerability Summary

Zebra from 2.3.0 before 7.0.0 contains a denial of service vulnerability that allows unauthenticated peers to evade misbehavior scoring by sending transactions or blocks with invalid transparent scripts. Attackers can flood mempool with script-failing transactions or serve forged v5 block bodies with altered scriptSig bytes to exhaust CPU and repeatedly stall block sync.
Severity Level
HIGH(8.7)
Published Date
Nov 8, 2026
Last Modified
Nov 13, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.43%Probability
Root Weakness (CWE)
CWE-755 ↗
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 >= 2.3.0 and < 7.0.0
  • ZcashFoundation zebra >= 1.0.0-beta.46 and < 18.0.0
Patched Versions
  • ZcashFoundation zebra 7.0.0
  • ZcashFoundation zebra 18.0.0

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

  • Nov 8, 2026Published
  • Nov 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 02:13 UTC