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    CVE-2026-104421

    Zebra before 6.2.1 contains an incomplete cleanup vulnerability that allows unauthenticated peers to block downloading of valid blocks by leaving rejected hashes in SentHashes. Attackers can send a contextually invalid block sharing an honest block's header hash, causing Request::KnownBlock to skip the honest block and keep nodes behind the tip.

    Published:Oct 2, 2026
    Last Modified:Oct 2, 2026
    EPS:Oct 2, 2026
    EPSS Score:
    CVSS Score:5.3

    Affected Products

    Vendor
    Zcashfoundation
    Product
    Zebra
    Vendor
    Zfnd
    Product
    Zebra

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-459 Incomplete Cleanup

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

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    CVE-2026-109363 (CVSS 8.7) — ZcashFoundation Zebra 6.4.0 before 6.4.2 parses version 6 transactions carrying a pre-NU6.3 consensus branch I…
    CVE-2026-104437 (CVSS 8.3) — Zebra before 4.4.0 contains a consensus divergence vulnerability in V5 transparent signature verification, com…
    CVE-2026-104436 (CVSS 6.3) — Zebra before 4.5.0 contains an uncontrolled resource consumption vulnerability that allows remote P2P peers to…
    CVE-2026-104435 (CVSS 8.3) — Zebra zebrad 4.4.0 and zebra-script 6.0.0 fail to enforce a ZIP-244 consensus rule, accepting V5 transparent i…
    CVE-2026-104434 (CVSS 7.1) — ZcashFoundation Zebra zebra-rpc before 8.0.0 and zebrad before 4.5.0 contain a reachable assertion in the z_li…
    CVE-2026-104432 (CVSS 6.9) — Zebra before 6.3.0 contains an improper exceptional condition check in ChainSync::obtain_tips that discards va…
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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High