CVE-2026-40881: Zebra: addr/addrv2 Deserialization Resource Exhaustion

Severity: high (CVSS 7.5 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: 2026-04-21 · updated 2026-10-26
Weakness: CWE-770

Description

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-network version 5.0.1, when deserializing addr or addrv2 messages, which contain vectors of addresses, Zebra would fully deserialize them up to a maximum length (over 233,000) that was derived from the 2 MiB message size limit. This is much larger than the actual limit of 1,000 messages from the specification. Zebra would eventually check that limit but, at that point, the memory for the larger vector was already allocated. An attacker could cause out-of-memory aborts in Zebra by sending multiple such messages over different connections. This vulnerability is fixed in zebrad version 4.3.0 and zebra-network version 5.0.1.

Affected products

ZcashFoundation zebra-network: before 5.0.1 — fixed in 5.0.1
ZcashFoundation zebra: before 4.3.1 — fixed in 4.3.1

How to fix

Upgrade to a fixed version: ZcashFoundation zebra-network 5.0.1; ZcashFoundation zebra 4.3.1. Check the vendor advisory for mitigations.

References

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