Executive brief
Zebra, a Zcash node implementation, is vulnerable to a denial-of-service attack that can completely shut down the node. An attacker with access to the node's remote control interface (RPC) can send a specially crafted address that causes the software to crash. This can be used to keep a node offline indefinitely, disrupting cryptocurrency operations such as mining or wallet services.
Technical details
The z_listunifiedreceivers RPC handler in zebrad contains a reachable assertion (panic) when processing a structurally valid but cryptographically invalid Unified Address. Specifically, the handler calls .expect() on a result from sapling_crypto::PaymentAddress::from_bytes that returns None for non-subgroup Jubjub points. Because the Zebra release profile is configured with panic = 'abort', this terminates the entire node process. An authenticated attacker (or unauthenticated if cookie auth is disabled) can trigger this via a network request to the RPC endpoint. The issue is fixed in zebrad v4.5.0 and zebra-rpc v8.0.0 by implementing proper error handling instead of a panic.
Affected products
- ZcashFoundation zebrad <= 4.4.1
- ZcashFoundation zebra-rpc <= 7.0.0
Timeline
- 2026-05-29: disclosed: Initial report via private GitHub Security Advisory
- 2026-07-02: advisory: Public advisory published