Is CVE-2026-104422 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-104422 being exploited in the wild.

How severe is CVE-2026-104422?

High severity, with a CVSS score of 7.5, published 2 October 2026.

Which products and versions are affected?

Zcash Foundation Zebra before 6.3.0.

Is there a fix for CVE-2026-104422?

Yes: fixed in 6.3.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-104422 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-104422?

Check whether you run Zcash Foundation Zebra at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-104422: Zebra block sync denial of service via coinbase scriptSig rewrite

CVE-2026-104422 · Severity: high · CVSS 7.5 · Published 2026-10-02

Zebra is a node for the Zcash blockchain that validates and synchronizes blocks with the network. A malicious peer can delay a node's discovery of the latest block by serving a forged copy that claims an old height, causing the node to discard it before validation; this can slow mining operations and prevent timely chain updates.

Technologies: Zcash Foundation Zebra. Vendors: Zcash Foundation.

Quick answers

Is CVE-2026-104422 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-104422 being exploited in the wild.
How severe is CVE-2026-104422?: High severity, with a CVSS score of 7.5, published 2 October 2026.
Which products and versions are affected?: Zcash Foundation Zebra before 6.3.0.
Is there a fix for CVE-2026-104422?: Yes: fixed in 6.3.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-104422 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-104422?: Check whether you run Zcash Foundation Zebra at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 6.3.0

Technical details

The vulnerability exploits Zcash's V5 transaction ID format, which excludes the coinbase scriptSig from the hash. An attacker copies a canonical block and rewrites only the coinbase scriptSig to encode height 1 while retaining the original header, so the block hash remains valid. The downloader reads the forged height from the unvalidated body, discards the block as too far behind the tip before consensus validation, and does not penalize or re-request from the supplying peer, delaying tip discovery by up to 10 seconds per attempt.

Affected products

Zcash Foundation Zebra before 6.3.0

Timeline

2026-08-11: disclosed: GitHub security advisory published
2026-10-02: advisory: NVD entry and CVE-2026-104422 published

References

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