What’s Vulnerable › Vulnerabilities

CVE-2026-104429: Zebra before 6.0.0-rc.0 Per-Peer Mempool Admission Bypass via P2P tx Messages

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-02 · updated 2026-10-02
• Weakness: CWE-770

Description

Zebra (zebrad) 5.0.0 before 6.0.0-rc.0 does not apply its per-peer mempool admission cap to transactions received as direct P2P tx messages, because these are queued without the sending peer recorded as their source. A remote inbound peer can push many unique transactions to occupy a disproportionate share of mempool admission slots, crowding out honest peers' transaction relay.

Affected products

• ZcashFoundation zebra: before 6.0.0-rc.0 — fixed in 6.0.0-rc.0

How to fix

Upgrade to a fixed version: ZcashFoundation zebra 6.0.0-rc.0. Check the vendor advisory for mitigations.

References

• https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-m9xx-8rcj-vmgp
• https://www.vulncheck.com/advisories/zebra-before-6.0.0-rc.0-per-peer-mempool-admission-bypass-via-p2p-tx-messages

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