CVE-2026-104426 Zebra before 6.1.0 Quadratic Complexity DoS via Block Transparent Value Check
Attackers can cause significant delays in Zcash node validation by submitting blocks with many minimal transactions, leading to denial of service.
- 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-2026-104426?
CVE-2026-104426 is a high-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 before 6.1.0 contains an inefficient algorithmic complexity vulnerability in remaining_transaction_value that clones the entire block-level spent-UTXO map per transaction during contextual verification. Attackers can mine or seed the mempool with roughly 26,000 minimal single-input transactions in one block, stalling every validating node for over 52 seconds.
Weakness: CWE-407
Which versions are affected by CVE-2026-104426?
How do I fix CVE-2026-104426?
No fix has been published for CVE-2026-104426 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-2026-104426 being exploited?
There is no known exploitation of CVE-2026-104426 in the wild and no public exploit code.
Sources
Also known as GHSA-4g24-549m-hp75, GHSA-g338-vc6m-x872.