Vulnerability in zebrad (CVE-2026-44498)
Summary
Vulnerability in zebrad (CVE-2026-44498). Data can be tampered with by attackers. Exploitable via MAX_BLOCK_SIGOPS. Mitigation: upgrade to 4.4.0 or later.
Original description
The description as published by the source.
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/ZcashFounda…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44498 has been found in zebrad.
Attackers can target a specific entry point like MAX_BLOCK_SIGOPS over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.5/10.
What to do: upgrade zebrad to 4.4.0 or later.
If unsure, ask your IT team or search "zebrad CVE-2026-44498" on the vendor's site.
CVE-2026-44498 (zebrad) — CWE-682 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: MAX_BLOCK_SIGOPS / zcashd / scriptSig / Sigops
Patched: 4.4.0 — apply immediately
Workaround: None.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-682) exists in zebrad. Attackers reach the vulnerable code path via MAX_BLOCK_SIGOPS without authentication.
Check the vendor advisory for the affected versions of zebrad. Attack surface: MAX_BLOCK_SIGOPS / zcashd / scriptSig / Sigops.
Severity: High (CVSS 7.5/10). Data can be tampered with by attackers.
Update to 4.4.0.
Workaround: None.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'zebrad' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'zebrad' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
zebradを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
None.パッチが適用されるまでの応急処置として、None. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade zebrad to 4.4.0ステージング環境で 4.4.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com