CVE-2026-104423 HIGH

CVE-2026-104423: Zebra before 6.2.1 Denial of Service via Uncapped V6 Shielded Proof Verification

Vendor Zcashfoundation

Product zebra

Weakness CWE-405

Published October 2, 2026

Last update October 2, 2026

View on NVD All CVEs

CVSS base score

8.7/10

Attack vector Network

Attack complexity Low

Privileges required None

User interaction None

Confidentiality —

Integrity —

CVSS vector

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

What the vulnerability does

01Description

Zebra (zebrad) before 6.2.1 contains an asymmetric resource consumption vulnerability that allows unauthenticated peers to stall block verification by pushing V6 mempool transactions with invalid Halo2 proofs. Attackers can flood the shared unprioritized Halo2 verification queue with zero-fee transactions carrying zero-filled Orchard and Ironwood proofs, causing nodes to fall behind the chain tip.

Key dates

02Disclosure timeline

October 2, 2026 CVE published

October 2, 2026 Record updated

External resources

03References

NVD — National Vulnerability Database https://nvd.nist.gov/vuln/detail/CVE-2026-104423 CWE — Common Weakness Enumeration https://cwe.mitre.org/data/definitions/405.html AskarLabs — CWE-405 write-up Asymmetric Resource Consumption (Amplification)