CVE-2026-52739: Repeated Non-Finalized Shielded Transaction Aborts Zebra Before Duplicate-Nullifier Rejection
Affects zebra-stateSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium : upgrade to 7.0.0 when convenient.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 7.0.0, 4.5.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 18 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade zebra-state to 7.0.0; zebrad to 4.5.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| crates.iozebra-state | Affected
| Fixed in
|
| crates.iozebrad | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and should be applied: upgrade to zebra-state 7.0.0 and zebrad 4.5.0 or later. The patch replaces the assert with a proper validation error to prevent process aborts. There is no configuration-level workaround; all default configurations are affected. Nodes must be restarted if they abort due to this issue until patched.
Description
ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a malicious block producer can terminate zebrad by placing the same shielded transaction in a non-finalized parent block and its child. In zebra-state/src/service/non_finalized_state/chain.rs, Chain::push originally inserted the transaction hash into tx_loc_by_hash and asserted uniqueness before updating shielded data and running the duplicate Sprout, Sapling, or Orchard nullifier checks. The repeated transaction therefore reached the transactions must be unique within a single chain assertion before contextual validation could reject it cleanly. Zebra release builds use panic equals abort, so the reachable assertion terminates the entire process; exploitation requires either two consecutive attacker-mined blocks or an attacker-mined child immediately after an honest block includes the attacker's shielded transaction. This issue is fixed in version 4.5.0.
References
- github.com/ZcashFoundation/zebra/security/advisories/GHSA-hhm7-qrv5-h4r6 (opens in a new tab)
- github.com/ZcashFoundation/zebra (opens in a new tab)
- github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/Cargo.toml (opens in a new tab)
- github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-consensus/src/transaction.rs (opens in a new tab)
- github.com/ZcashFoundation/zebra/blob/d4cd662c716382f6397d2a730148025a1ca79fec/zebra-state/src/service/non_finalized_state/chain.rs (opens in a new tab)