Vulnerability · Published Oct 2, 2026 · Assigned by VulnCheck

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

High 7.5

In plain English

A high-severity security flaw in zebra from ZcashFoundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.3%top 72.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
ZcashFoundation	zebra	0 – before 6.2.1

Weakness: CWE-405 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-2p4c-3q4q-p463) vendor-advisory
VulnCheck Advisory: Zebra before 6.2.1 Denial of Service via Uncapped V6 Shielded Proof Verification third-party-advisory