CVE-2026-44498CWE-682

ZEBRA: Block Validator Undercounts Coinbase and P2SH Sigops

Critical · published May 8, 2026

CVSS v4.0

9.2

EPSS

Percentile

30.8

In the wild

Unconfirmed

What it is

ZEBRA is a Zcash node written entirely in Rust. Prior to version 4.4.0, Zebra's block validator undercounts transparent signature operations against the 20000-sigop block limit (MAX_BLOCK_SIGOPS), allowing it to accept blocks that zcashd rejects with bad-blk-sigops. A miner who produces such a block can split the network: Zebra nodes follow the offending chain while zcashd nodes do not. This issue has been patched in version 4.4.0.

The record

Technical detail

CVSS v4.0: 9.2 · CRITICAL
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
EPSS: 0.00380 · 30.8th percentile
Weakness: CWE-682 · Incorrect Calculation
Published: 2026-05-08T15:09Z

EPSS history

Timeline

08 MAY 15:09Z
ZEBRA: Block Validator Undercounts Coinbase and P2SH Sigops
cvelistv5