CVE-2026-52738: Zebra Finalized Address Balance Credit-first Overflow Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w834-cf6p-9m9w",
  "modified" : "2026-07-02T19:44:54Z",
  "published" : "2026-07-02T19:44:54Z",
  "aliases" : [ "CVE-2026-52738" ],
  "summary" : "Zebra: Finalized address balance credit-first overflow on consensus-valid blocks",
  "details" : "### Am I affected\n\nYou are affected if:\n\n1. You run `zebrad` up to and including `v4.4.1`.\n2. Your node processes blocks on any Zcash network.\n\n### Summary\n\nThe finalized transparent address balance writer processes all newly-created outputs (credits) before processing spent outputs (debits) within the same block. A consensus-valid block containing a long chain of same-address transparent self-spends can cause the intermediate per-address balance during the credit pass to exceed `MAX_MONEY`, triggering a panic in the finalized state writer.\n\nBecause the triggering block is consensus-valid (zcashd accepts it), the panic recurs on restart when the node re-encounters the same block. This creates a persistent chain halt that can only be resolved by a software patch.\n\n### Details\n\nThe finalized state writer at `zebra-state/src/service/finalized_state/zebra_db/transparent.rs` iterates all transaction outputs in a block and credits them to per-address balances before iterating inputs and debiting spent outputs. When a block contains many transparent self-spends to the same address, the intermediate credit-only balance can exceed the `MAX_MONEY` supply cap even though the final net balance (credits minus debits) is valid.\n\nThe code panics on the intermediate overflow via `.expect()` on the balance addition. Under Zebra's `panic = \"abort\"` release profile, this terminates the process. On restart, the node re-downloads and re-processes the same consensus-valid block, triggering the same panic.\n\nAn attacker with approximately 1,100–2,100 ZEC and mining capability can construct a block that permanently halts all Zebra nodes. The attacker recovers their capital (the self-spends return funds to the same address), so the net cost is the mining effort only.\n\n### Patches\n\nPatched in Zebra 4.4.2. The fix processes credits and debits together per transaction rather than all credits then all debits, matching zcashd's approach.\n\n### Workarounds\n\nNo workaround is available. Upgrade to Zebra 4.4.2.\n\n### Impact\n\nA single consensus-valid mined block can permanently halt all Zebra nodes on the network. The halt persists across restarts. Recovery requires deploying a patched version. Downstream consumers (light wallets, exchanges, mining infrastructure) lose service for the duration of the halt.\n\n### Credit\n\nReported by `@sangsoo-osec`.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "zebra-state"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.0.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 6.0.0"
    }
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "zebrad"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.5.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.4.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-w834-cf6p-9m9w"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ZcashFoundation/zebra"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-248" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-02T19:44:54Z",
    "nvd_published_at" : null
  }
}