SB2026051171 - Multiple vulnerabilities in Zcash

Description

This security bulletin contains information about 2 vulnerabilities.

1) Improper control of a resource through its lifetime (CVE-ID: N/A)

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper state management in zcashd block ingestion when processing a poisoned NU5+ block body before the canonical body. A remote attacker can send a specially crafted block body with mutated V5 transaction authorizing data to cause a denial of service.

Successful exploitation requires winning a P2P delivery race for a newly mined NU5+ block, and the targeted node can remain stalled on a stale chain tip until manual recovery.

2) Input validation error (CVE-ID: N/A)

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to improper input validation in the V4 Sapling transaction parser when processing malformed raw block data containing a non-zero valueBalanceSapling with no Sapling spends or outputs. A remote user can embed a specially crafted malformed transaction directly into raw block bytes to cause a denial of service.

Exploitation requires a miner or custom raw block producer to place the malformed raw transaction bytes directly into a block, because ordinary zcashd relay and mining canonicalize the encoding before block production.

Remediation

Install update from vendor's website.

References

• https://github.com/zcash/zcash/security/advisories/GHSA-rpcw-q5mr-gq35
• https://github.com/zcash/zcash/security/advisories/GHSA-3jg6-49c6-q99v
• https://github.com/zcash/zcash/blob/2c63e9aa08cb170b0feb374161bea94720c3e1f5/src/primitives/transaction.h