CVE-2026-104436: Allocation of Resources Without Limits or Throttling in ZcashFoundation zebra
Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability that allows remote P2P peers to exhaust blocking-pool threads by sending oversized block locator vectors. Attackers can send getblocks or getheaders messages with up to 65,535 locator hashes, triggering per-hash chain lookups that degrade block validation, RPC, and mempool performance.
AI Analysis
Technical Summary
CVE-2026-104436 is an uncontrolled resource consumption vulnerability in Zebra prior to version 4.5.0. Remote P2P peers can send getblocks or getheaders messages containing up to 65,535 locator hashes, causing the software to perform per-hash chain lookups that exhaust blocking-pool threads. This results in degraded performance of block validation, RPC, and mempool operations.
Potential Impact
The vulnerability allows remote attackers to degrade the performance of Zebra nodes by exhausting blocking-pool threads, impacting block validation, RPC responsiveness, and mempool processing. There is no indication of code execution or data compromise, but availability and performance are affected.
Mitigation Recommendations
A fix is available in Zebra version 4.5.0 and later. Users should upgrade to version 4.5.0 or newer to remediate this vulnerability. No other mitigation guidance is provided.
CVE-2026-104436: Allocation of Resources Without Limits or Throttling in ZcashFoundation zebra
Description
Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability that allows remote P2P peers to exhaust blocking-pool threads by sending oversized block locator vectors. Attackers can send getblocks or getheaders messages with up to 65,535 locator hashes, triggering per-hash chain lookups that degrade block validation, RPC, and mempool performance.
CVSS v4.0
Score 6.3medium
Affected software
ZcashFoundation
zebra
ZcashFoundation
zebra
pkg: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-2026-104436 is an uncontrolled resource consumption vulnerability in Zebra prior to version 4.5.0. Remote P2P peers can send getblocks or getheaders messages containing up to 65,535 locator hashes, causing the software to perform per-hash chain lookups that exhaust blocking-pool threads. This results in degraded performance of block validation, RPC, and mempool operations.
Potential Impact
The vulnerability allows remote attackers to degrade the performance of Zebra nodes by exhausting blocking-pool threads, impacting block validation, RPC responsiveness, and mempool processing. There is no indication of code execution or data compromise, but availability and performance are affected.
Mitigation Recommendations
A fix is available in Zebra version 4.5.0 and later. Users should upgrade to version 4.5.0 or newer to remediate this vulnerability. No other mitigation guidance is provided.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-02T00:50:26.604Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6abf99b0a43b0b3b89b26949
Added to database: 10/02/2026, 11:46:56 UTC
Last enriched: 10/02/2026, 12:01:57 UTC
Last updated: 10/03/2026, 03:07:42 UTC
Views: 12
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