CVE-2026-104427
HIGH 8.2Zebra before 6.1.0 contains an incomplete cleanup vulnerability in the state write task that allows remote unauthenticated peers to stall node synchronization by poisoning parent_error_map. Attackers can deliver a coinbase-malleated block sharing a canonical block's hash before it propagates, causing the next canonical block to be rejected and stalling the node for roughly 2,000 blocks.
Severe if exploited (CVSS 8.2), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 23rd percentile
Impact if exploited
8.2CVSS 4.0 · HIGH
- ConfidentialityNone
- IntegrityNone
- AvailabilityHigh
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ⚠Complexity: Needs a race window or specific setup
- ⚠Requirements: Specific conditions must be present
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Data snapshot:
Weakness (CWE)
- CWE-459: Incomplete Cleanup
CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References and research data (JSON)
All CVSS metrics
- HIGH 8.2 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - MEDIUM 5.9 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - HIGH 8.2 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - MEDIUM 5.9 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Advisories
- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-8gxx-hc65-vv82 CVE record · VulnCheck · Updated 2026-10-02T11:38:07.777Z
NVD · CVE-2026-104427 · Updated 2026-10-05T15:17:15.030 - https://www.vulncheck.com/advisories/zebra-before-6.1.0-chain-stall-via-stale-parent-error-map-entry CVE record · VulnCheck · Updated 2026-10-02T11:38:07.777Z
NVD · CVE-2026-104427 · Updated 2026-10-05T15:17:15.030 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-91438 EUVD · EUVD-2026-91438