ZEBRA: Permanent Block Discovery Halt via Gossip Queue Saturation and Syncer Poisoning
ZEBRA is a Zcash node written entirely in Rust. Prior to version 4.4.0, a composite denial-of-service vulnerability in Zebra's block discovery pipeline allows an unauthenticated remote attacker to permanently halt all new block discovery on a targeted node. The attack exploits three independent weaknesses in the gossip, syncer, and download subsystems — all exercisable from a single TCP connection — to create a monotonically growing block deficit that never self-heals. This issue has been patched in version 4.4.0.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-44499
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 18:23 UTC · Revision 1
Source evidence
ZEBRA: Permanent Block Discovery Halt via Gossip Queue Saturation and Syncer Poisoning
core-osv · Original sourcePublished 8 May 2026, 15:11 UTC
ZEBRA is a Zcash node written entirely in Rust. Prior to version 4.4.0, a composite denial-of-service vulnerability in Zebra's block discovery pipeline allows an unauthenticated remote attacker to permanently halt all new block discovery on a targeted node. The attack exploits three independent weaknesses in the gossip, syncer, and download subsystems — all exercisable from a single TCP connection — to create a monotonically growing block deficit that never self-heals. This issue has been patched in version 4.4.0.
osv:CVE-2026-44499
Complete source record
{
"id": "55395ef712f2ce2e1740d90f0334e950013b95c87852b395bb221637b3b797a4",
"url": "https://osv.dev/vulnerability/CVE-2026-44499",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ZEBRA: Permanent Block Discovery Halt via Gossip Queue Saturation and Syncer Poisoning",
"summary": "ZEBRA is a Zcash node written entirely in Rust. Prior to version 4.4.0, a composite denial-of-service vulnerability in Zebra's block discovery pipeline allows an unauthenticated remote attacker to permanently halt all new block discovery on a targeted node. The attack exploits three independent weaknesses in the gossip, syncer, and download subsystems — all exercisable from a single TCP connection — to create a monotonically growing block deficit that never self-heals. This issue has been patched in version 4.4.0.",
"evidence": "osv:CVE-2026-44499",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-44499",
"aliases": [
"CVE-2026-44499",
"GHSA-h9hm-m2xj-4rq9"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/zcashfoundation/zebra",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "589d64b9b7ea6ab4c32ecab41ba6b74f26907940"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
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},
{
"fixed": "4.4.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
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},
{
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}
],
"source": "DESCRIPTION"
}
]
}
}
],
"versions": [
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"v1.0.0-alpha.3",
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],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-44499.json"
}
}
],
"modified": "2026-10-28T02:30:38.300365246Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44499.json",
"https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-h9hm-m2xj-4rq9",
"https://nvd.nist.gov/vuln/detail/CVE-2026-44499"
],
"provider_metadata": {
"cwe_ids": [
"CWE-770"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44499.json"
}
},
"related_cves": [
{
"value": "CVE-2026-44499",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 505664,
"published_at": "2026-05-08T15:11:24.837+00:00"
}