ZcashFoundation Zebra up to 4.3.x TCP Connection allocation of resources

Summaryinfo

A vulnerability labeled as problematic has been found in ZcashFoundation Zebra up to 4.3.x. This vulnerability affects unknown code of the component TCP Connection Handler. Such manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-44499. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in ZcashFoundation Zebra up to 4.3.x. Affected by this issue is an unknown part of the component TCP Connection Handler. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-44499 since 05/06/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 4.4.0 eliminates this vulnerability.

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Productinfo

Vendor

• ZcashFoundation

Name

• Zebra

Version

• 4.0
• 4.1
• 4.2
• 4.3

Website

• Product: https://github.com/ZcashFoundation/zebra/

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