SB2026071456 - Multiple vulnerabilities in Zcash

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Main Vulnerability Database SB2026071456

SB2026071456 - Multiple vulnerabilities in Zcash

Published: July 14, 2026 Updated: July 20, 2026

Security Bulletin ID SB2026071456
CSH Severity
High
Patch available
YES
Number of vulnerabilities 5
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

High 20% Medium 80%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 5 vulnerabilities.


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

CWE-ID: CWE-20 - Improper input validation

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to permanently store unwanted data on-chain at minimal cost.

The vulnerability exists due to improper input validation in Orchard proof data handling when processing transactions containing large padded Orchard proofs. A remote attacker can submit a specially crafted transaction to permanently store unwanted data on-chain at minimal cost.

The issue does not present a consensus violation or divergence risk.


2) Improper Check for Unusual or Exceptional Conditions (CVE-ID: N/A)

CWE-ID: CWE-754 - Improper Check for Unusual or Exceptional Conditions

CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


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

The vulnerability exists due to improper handling of body-derived validation failures in CheckBlock()/AcceptBlock() and shared CBlockIndex state when processing a malformed NU5+ block body for a genuine header near MAX_BLOCK_SIZE. A remote attacker can submit a specially crafted malformed block body to cause a denial of service.

The issue affects nodes that ingest the malformed body before the genuine body for the same header, causing the genuine block at that height to be rejected until restart.


3) Resource exhaustion (CVE-ID: N/A)

CWE-ID: CWE-400 - Resource exhaustion

CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


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

The vulnerability exists due to uncontrolled resource consumption in zcashd block processing when handling repeated P2P block messages for a disk-persisted invalid pool-delta block. A remote attacker can replay the same specially crafted block message to cause a denial of service.

The initial block must have valid proof-of-work and an invalid aggregate value-pool delta, after which identical unauthenticated P2P replays can repeatedly append duplicate block bodies to disk because the block remains header-only and is not marked invalid.


4) Always-Incorrect Control Flow Implementation (CVE-ID: N/A)

CWE-ID: CWE-670 - Always-Incorrect Control Flow Implementation

CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


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

The vulnerability exists due to improper validity status handling in AcceptBlock() and CheckBlock() when processing a mutated NU5 block body that exceeds MAX_BLOCK_SIGOPS before auth commitment validation runs. A remote attacker can send a specially crafted block body to cause a denial of service.

The issue affects NU5-active networks and requires the poisoned block body to be delivered before the genuine body for the same header.


5) Insufficient verification of data authenticity (CVE-ID: N/A)

CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to counterfeit funds within the Orchard pool, including double-spend notes under multiple nullifiers and authorize spends of other users' notes.

The vulnerability exists due to improper constraint enforcement in the Orchard Action circuit variable-base scalar-multiplication gadget in halo2_gadgets when generating Orchard proofs against an under-constrained base point. A remote attacker can produce a malformed proof with a freely chosen base value to counterfeit funds within the Orchard pool, including double-spend notes under multiple nullifiers and authorize spends of other users' notes.

The zero-knowledge property hides the malformed witness, leaving no distinguishing on-chain trace.


Remediation

Install update from vendor's website.

References