CVE-2026-104419 Zebra before 6.3.0 Honest Peer Banning via Far-Ahead FindBlocks Hashes
Remote attackers can ban honest peers by exploiting hash validation logic, degrading the node's peer set and increasing eclipse attack risk.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-104419?
CVE-2026-104419 is a medium-severity denial of service vulnerability in ZcashFoundation zebra, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Zebra (zebrad) 4.5.0 before 6.3.0 discards which peer supplied the block hashes in FindBlocks responses, then assigns 100 misbehavior points, the ban threshold, to whichever peer serves a requested block more than 50,000 heights above the tip. A remote peer can return real far-ahead hashes to a syncing node so that honest peers get banned, eroding its peer set and raising eclipse risk.
Weakness: CWE-345
Which versions are affected by CVE-2026-104419?
How do I fix CVE-2026-104419?
No fix has been published for CVE-2026-104419 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-104419 being exploited?
There is no known exploitation of CVE-2026-104419 in the wild and no public exploit code.
Sources
Also known as GHSA-qhr3-cvch-5fh2, GHSA-rrh7-6j2w-crgw.