CVE-2026-44498
HIGH7.5EPSS 0.01%Zebra's Block Validator Undercounts Coinbase and P2SH Sigops
描述
Zebra's block validator undercounts transparent signature operations against the 20000-sigop block limit (`MAX_BLOCK_SIGOPS`), allowing it to accept blocks that `zcashd` rejects with `bad-blk-sigops`. A miner who produces such a block can split the network: Zebra nodes follow the offending chain while `zcashd` nodes do not. Two distinct undercounts: #### A: Coinbase Hidden Legacy Sigops `zcashd`'s `GetLegacySigOpCount()` includes the coinbase input's `scriptSig`. Zebra's `Sigops` impl skipped the coinbase input entirely, so up to ~98 sigops (the 100-byte coinbase script length cap, less the height prefix) could be hidden inside the coinbase `scriptSig` without being charged against the block limit. #### B: Aggregate P2SH Sigops. `zcashd`'s `GetP2SHSigOpCount()` parses each P2SH input's redeem script with `accurate=true` and sums those sigops into the block-wide total via `ConnectBlock`. The check is per-block, not per-transaction, and the limit applies regardless of who mines the offending block — a miner just needs to include enough P2SH-spending transactions whose redeem scripts together exceed 20000 sigops. Zebra computed P2SH sigops only on the mempool-acceptance path (used for ZIP-317 weighting) and never accumulated them during block validation. A block whose aggregate redeem-script sigops exceed 20000 (e.g. 1334 P2SH spends × 15 sigops = 20010) would be accepted by Zebra and rejected by `zcashd`. ### Patches Fixed in this release: https://github.com/ZcashFoundation/zebra/releases/tag/v4.4.0. ### Workarounds None. Operators relying on Zebra for consensus should upgrade. ### Resources - `MAX_BLOCK_SIGOPS` constant inherited from Bitcoin via the Zcash protocol spec's §7.6 catch-all "Other rules inherited from Bitcoin", tracked for explicit documentation in [zcash/zips#568](https://github.com/zcash/zips/issues/568). - `zcashd` `GetLegacySigOpCount`: <https://github.com/zcash/zcash/blob/v6.11.0/src/main.cpp#L826-L836> - `zcashd` `GetP2SHSigOpCount`: <https://github.com/zcash/zcash/blob/v6.11.0/src/main.cpp#L840-L852> - `zcashd` `ConnectBlock` aggregates per-tx sigops and compares against `MAX_BLOCK_SIGOPS`.
受影響套件(1)
- crates.io/zebradfrom 0, < 4.4.0
CVSS 分數
| 來源 | 版本 | 嚴重程度 | 向量 |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |