# CVE-2026-44497: Zcash Foundation Zebra consensus divergence in sighash handling

Source: https://junglewise.ai/threats/cve-2026-44497-zcash-foundation-zebra-consensus-divergence-in-sighash-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-07. Updated: 2026-05-13  
License: CC BY 4.0 with a link back

CVE-2026-44497 · Severity: critical · CVSS 9.1 · Published 2026-05-07

Zebra, a Zcash node implementation, contains a vulnerability in how it validates certain transaction signatures. A malicious actor could exploit this to cause a 'consensus split,' where Zebra nodes disagree with other nodes on the network about which transactions are valid. This can lead to network partitioning, service disruptions, and potential double-spend attacks, undermining the reliability of the blockchain.

Technologies: [zebra-script (crates.io)](https://junglewise.ai/threats/technologies/zebra-script), [zebrad (crates.io)](https://junglewise.ai/threats/technologies/zebrad). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io).

## Quick answers

**Is CVE-2026-44497 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44497 being exploited in the wild.

**How severe is CVE-2026-44497?** Critical severity, with a CVSS score of 9.1, published 7 May 2026.

**Which products and versions are affected?** zebra-script (crates.io) <= 5.0.1, SEMVER:introduced=0,fixed=6.0.0; zebrad (crates.io) < 4.4.0, SEMVER:introduced=0,fixed=4.4.0.

**Is there a fix for CVE-2026-44497?** Yes. zebra-script (crates.io): upgrade to 6.0.0 or later; zebrad (crates.io): upgrade to 4.4.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44497 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44497?** Check whether you run zebra-script (crates.io) or zebrad (crates.io) 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

- zebra-script (crates.io): upgrade to 6.0.0 or later

  ```sh
  cargo update -p zebra-script
  ```

- zebrad (crates.io): upgrade to 4.4.0 or later

  ```sh
  cargo update -p zebrad
  ```


## Technical details

A vulnerability exists in Zebra's transparent transaction verification where insufficient error handling during sighash computation leads to a stale buffer being used. When a Rust callback returns 'None' for an undefined hash type, the FFI bridge fails to update the C++ sighash buffer, leaving the digest from a previous valid signature validation intact. An attacker can exploit this by crafting a script with a valid OP_CHECKSIGVERIFY followed by an OP_CHECKSIG using an invalid hash type; Zebra will incorrectly validate the second signature against the stale digest while other implementations (like zcashd) reject it. This results in a consensus split. The issue is fixed in zebrad 4.4.0 and zebra-script 6.0.0.

## Affected products

- ZcashFoundation zebra-script <= 5.0.1
- ZcashFoundation zebrad < 4.4.0

## Identifiers

- CVE-2026-44497
- GHSA-gq4h-3grw-2rhv

## Timeline

- 2026-05-02: disclosed
- 2026-05-07: advisory
- 2026-05-08: other: NVD published

## References

- [https://api.github.com/users/sangsoo-osec](https://api.github.com/users/sangsoo-osec)
- [https://github.com/sangsoo-osec](https://github.com/sangsoo-osec)
- [https://api.github.com/users/sangsoo-osec/gists%7B/gist_id%7D](https://api.github.com/users/sangsoo-osec/gists%7B/gist_id%7D)
- [https://api.github.com/users/sangsoo-osec/repos](https://api.github.com/users/sangsoo-osec/repos)
- [https://avatars.githubusercontent.com/u/129559837?v=4](https://avatars.githubusercontent.com/u/129559837?v=4)
- [https://api.github.com/users/sangsoo-osec/events%7B/privacy%7D](https://api.github.com/users/sangsoo-osec/events%7B/privacy%7D)

## Related threats

- [ZcashFoundation Zebra assertion panic in address book mempool update](https://junglewise.ai/threats/cve-2026-52829-zcashfoundation-zebra-assertion-panic-in-address-book-mempool)
- [ZcashFoundation Zebra process abort via repeated shielded transactions](https://junglewise.ai/threats/cve-2026-52739-zcashfoundation-zebra-process-abort-via-repeated-shielded)
- [ZcashFoundation Zebra denial of service via balance overflow in state writer](https://junglewise.ai/threats/cve-2026-52738-zcashfoundation-zebra-denial-of-service-via-balance-overflow-in)
- [Zcash Zebra sync restart poisoning via above-lookahead block](https://junglewise.ai/threats/cve-2026-52737-zcash-zebra-sync-restart-poisoning-via-above-lookahead-block)
- [ZcashFoundation Zebra block suppression via same-header body poisoning](https://junglewise.ai/threats/cve-2026-52736-zcashfoundation-zebra-block-suppression-via-same-header-body)