{"schema":"threatline.record/2","record":{"id":"CVE-2026-104421","aliases":["GHSA-x93j-mj2f-q338"],"summary":"Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout","details":"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.","categories":["Unclassified"],"product":"zebra","vendor":"ZcashFoundation","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-104421","source_modified_at":"2026-10-02T12:28:10.585Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"zebra","vendor":"ZcashFoundation","versions":[{"version":"0","status":"affected","versionType":"semver","lessThan":"6.2.1"},{"version":"6.2.1","status":"unaffected","versionType":"semver"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-104421","source_modified_at":"2026-10-02T12:28:10.585Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"zebra","ecosystem":null},"version":"6.2.1","basis":"first unaffected version stated in the CVE record"}],"cvss":6.9,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00304,"percentile":0.22039,"score_date":"2026-10-23"},"published_at":"2026-10-02T11:38:02.456Z","modified_at":"2026-10-02T12:28:10.585Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-104421","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-02T12:28:10.585Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-104421","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-x93j-mj2f-q338","tags":["vendor-advisory"]},{"source":"CVE List","url":"https://www.vulncheck.com/advisories/zebra-before-6.2.1-block-download-denial-of-service-via-knownblock-senthashes-lockout","tags":["third-party-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-10-02T12:27:43.846358Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-02T12:28:10.585Z","content_hash":"f3381024e8e9aec00e63bf40dd503814d139efe164798933117b7907e329b450"}}