GHSA-cwfq-rfcr-8hmp: Zebra's Transparent SIGHASH_SINGLE Handling Diverges from zcashd for Corresponding Outputs

Should you act?

• Only if you depend on one of the packages below, directly or transitively, in a vulnerable version. Check your lockfile with cargo audit.
• No CVE has been assigned, so it will not appear in CVE-based scanners that ignore GitHub advisories. npm audit, pip-audit and Dependabot do read GitHub advisories.

Affected packages

Details

Zebra Transparent SIGHASHSINGLE Corresponding-Output Handling Diverges From zcashd

Summary For V5+ transparent spends, Zebra and zcashd disagree on the same consensus rule: SIGHASHSINGLE must fail when the input index has no corresponding output. zcashd treats this as consensus-invalid under ZIP-244, while Zebra's transparent verification path computes a digest for the missing-output case instead of failing.

The result is a direct block-validity split. A malformed V5 transparent transaction can be accepted by Zebra, retained in Zebra's mempool, selected into Zebra getblocktemplate, mined into a block, and then rejected by zcashd.

Details Validated code revisions used during analysis:

- zcashd: 2c63e9aa08cb170b0feb374161bea94720c3e1f5 - Zebra: a905fa19e3a91c7b4ead331e2709e6dec5db12cb

Scope note:

- earlier triage material grouped pre-V5 and V5 behavior together; - re-execution on the pinned revisions did not reproduce the claimed pre-V5 / V4 reject-side behavior; - this advisory therefore covers the V5+ / ZIP-244 variant only.

zcashd side:

CVSS: 9.2 (v4.0) 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

Sources and references

1. GitHub Advisory GHSA-cwfq-rfcr-8hmp github.com
2. github.com github.com
3. github.com github.com

Critical crates.io (Rust) advisories · Today’s Security Digest