CVE-2026-104436

6.3 mediumEPSS 0.3%

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 4.0: 6.3CVSS: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 3.1: 3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.3% chance of exploitation in the next 30 days; higher than 19% of CVEs (scores of 2026-10-25)
CWE: CWE-770
Published: 2026-10-02
Modified: 2026-10-02
Record from: the NVD, synced 2026-10-19

Packages (OSV)

Advisory	Ecosystem	Package	Affected	Fixed in
GHSA-443g-gwgp-49x4	crates.io	zebrad	<4.5.0	4.5.0
GHSA-443g-gwgp-49x4	crates.io	zebra-chain	<8.0.0	8.0.0

References

https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-443g-gwgp-49x4
https://www.vulncheck.com/advisories/zebra-before-4.5.0-cpu-amplification-via-uncapped-getblocks-getheaders-locator-length

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