Vulnerability · Published May 8, 2026 · Assigned by GitHub_M

CVE-2026-44498ZEBRA: Block Validator Undercounts Coinbase and P2SH Sigops

Critical 9.2

In plain English

A critical-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 21% of all known vulnerabilities).

Severity (CVSS 4.0)9.2Critical

Exploit odds (30 days)0.3%top 79.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
ZcashFoundation	zebra	< 4.4.0

Weakness: CWE-682 · 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

References

https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-jv4h-j224-23cc x_refsource_CONFIRM
https://github.com/ZcashFoundation/zebra/releases/tag/v4.4.0 x_refsource_MISC