CVE-2026-104436 PUBLISHED

Zebra before 4.5.0 CPU Amplification via Uncapped getblocks/getheaders Locator Length

Assigner: VulnCheck
Reserved: 02.10.2026 Published: 02.10.2026 Updated: 02.10.2026

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 Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS Score: 3.7

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	ZcashFoundation
Product	zebra
Versions	Default: unaffected affected from 0 to 4.5.0 (excl.) Version 4.5.0 is unaffected

Vendor	ZcashFoundation
Product	zebra
Versions	Default: unaffected affected from 0 to 8.0.0 (excl.) Version 8.0.0 is unaffected

CVE-2026-104436 PUBLISHED

Zebra before 4.5.0 CPU Amplification via Uncapped getblocks/getheaders Locator Length

Metrics

Product Status

Credits

References

Problem Types