CVE-2026-109365: Insufficient Verification of Data Authenticity in ZcashFoundation zebra
Description
Zebra before 6.4.0 contains an uncontrolled resource consumption vulnerability that allows unauthenticated peers to force full proof verification by serving forged block bodies with valid header hashes. Attackers can flip authorizing-only bytes such as a coinbase scriptSig, wasting Sapling, Orchard, and Ironwood proof verification without penalty and stalling sync for 67 seconds.
CVSS v4.0
Score 6.3medium
Affected software
ZcashFoundation
zebra
pkg:cargo/github/ZcashFoundation/zebraRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-109365 describes an uncontrolled resource consumption vulnerability in ZcashFoundation's Zebra software prior to version 6.4.0. An attacker can serve forged block bodies with valid header hashes to unauthenticated peers, triggering full proof verification unnecessarily. By flipping authorizing-only bytes such as a coinbase scriptSig, the attacker causes the system to waste computational resources verifying Sapling, Orchard, and Ironwood proofs, resulting in a sync stall lasting approximately 67 seconds.
Potential Impact
The vulnerability leads to denial-of-service-like conditions by stalling synchronization processes due to wasted proof verification resources. It does not require authentication and can be triggered remotely by unauthenticated peers. There is no indication of data compromise or privilege escalation.
Mitigation Recommendations
A fix is available in Zebra version 6.4.0. Users should upgrade to version 6.4.0 or later to remediate this vulnerability. No additional mitigations are specified.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-12T14:21:32.595Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6acd0c192cdf04f656b11c1c
Added to database: 10/12/2026, 16:34:33 UTC
Last enriched: 10/12/2026, 16:48:45 UTC
Last updated: 10/12/2026, 21:46:36 UTC
Views: 10
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