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CVE-2026-52737 medium CVSS 5.3

Vulnerability in zebra-consensus (CVE-2026-52737)

Summary

Vulnerability in zebra-consensus (CVE-2026-52737). Risk of unauthorized operations or information disclosure. Exploitable via zebrad. Mitigation: upgrade to 7.0.0 or later.

Original description

The description as published by the source.

Am I affected

You are affected if:

  1. You run zebrad up to and including v4.4.1.
  2. Your node accepts inbound P2P connections and is syncing or catching up to the chain tip.

Summary

A malicious peer can answer Zebra's outbound getblocks/FindBlocks request with a small two-hash inventory, then serve a syntactically valid block whose coinbase height is far above the victim's local tip. The AboveLookaheadHeightLimit error in the sync download pipeline triggers a global sync restart rather than being scoped to the offending peer. The peer is never scored or disconnected because the error type does not carry the advertiser address.

On mainnet, each successful cycle imposes a 67-second sync restart delay. All in-flight downloads from honest peers are cancelled on each restart.

Details

The bug is the interaction of three layers:

  1. The syncer promotes unvalidated FindBlocks peer responses into concrete download schedules without checking that the advertised hashes are plausible chain extensions.

  2. When a downloaded block's coinbase height exceeds tip + VERIFICATION_PIPELINE_DROP_LIMIT, the sync downloader returns BlockDownloadVerifyError::AboveLookaheadHeightLimit. This error variant carries only the block height and hash, not the advertiser peer address.

  3. The sync error handler in handle_block_response only sends misbehaviour scores for BlockDownloadVerifyError::Invalid errors that carry an advertiser_addr and have a nonzero `misbehavi…

Source: GitHub Security Advisories (Global) 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-2026-52737 has been found in zebra-consensus.
Attackers can target a specific entry point like zebrad over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade zebra-consensus to 7.0.0 or later.
If unsure, ask your IT team or search "zebra-consensus CVE-2026-52737" on the vendor's site.

CVE-2026-52737 (zebra-consensus) — CWE-345 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: zebrad / getblocks / FindBlocks / AboveLookaheadHeightLimit
Patched: 7.0.0 — apply immediately
Workaround: No configuration-level workaround is available.
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.

❓ What is the problem

A vulnerability (CWE-345) exists in zebra-consensus. Attackers reach the vulnerable code path via zebrad without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of zebra-consensus. Attack surface: zebrad / getblocks / FindBlocks / AboveLookaheadHeightLimit.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 7.0.0.

🛡️ Workaround

Workaround: No configuration-level workaround is available.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'zebra-consensus' . 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

  1. 1
    Identify exposure identify 
    grep -r 'zebra-consensus' . | 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 zebra-consensus を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    No configuration-level workaround is available.

    パッチが適用されるまでの応急処置として、No configuration-level workaround is available. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade zebra-consensus to 7.0.0

    ステージング環境で 7.0.0 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。

  4. 4
    Post-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

rust zebra-consensus
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.0.0"}]}]
rust zebrad
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.0"}]}]
crates.io zebra-consensus
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"7.0.0"}]}]
crates.io zebrad
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.5.0"}]}]

References

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