CVE-2026-104424

Zebra before 6.1.0 Incorrect Block Size Calculation in getblocktemplate

6.3 Medium

Zebra before 6.1.0 contains an incorrect calculation vulnerability in its ZIP-317 block template selector that omits header and transaction-count size from the block budget. Attackers can place valid selectable transactions in a victim miner's mempool to shape templates into oversized blocks, causing rejection and wasted proof-of-work.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: Low

Exploit likelihood

0.27%Unchanged since Oct 3, 2026

What each source reports

CVE List Score used 6.3

Zebra before 6.1.0 Incorrect Block Size Calculation in getblocktemplate

Record: CVE-2026-104424
CVSS 4.0: 6.3 MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS 3.1: 3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-131
Updated: 2026-11-02

EUVDEUVD-2026-91435 6.3

Record: EUVD-2026-91435
CVSS 4.0: 6.3 MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-3xx8-299f-8q53 6.3

Zebra before 6.1.0 contains an incorrect calculation vulnerability in its ZIP-317 block template...

Record: GHSA-3xx8-299f-8q53
CVSS 4.0: 6.3 MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-131
Updated: 2026-11-02

NVD 6.3

Record: CVE-2026-104424
CVSS 4.0: 6.3 MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness: CWE-131
Updated: 2026-11-02

OSV 6.3

Zebra before 6.1.0 Incorrect Block Size Calculation in getblocktemplate

Record: CVE-2026-104424
CVSS 4.0: 6.3 MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Weakness: CWE-131
Updated: 2026-11-02

Affected products

zcashfoundation zebra

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-104424 is a medium vulnerability (CVSS 6.3) in Zcashfoundation Zebra, published October 2, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.27%, the 19th percentile. No source names a fixed version.