CVE-2026-106439: Hydra-Ecosystem Hydra

High severity, CVSS 8.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Hydra is a framework for elegantly configuring complex applications. From 1.3.4 until 1.3.7 and 1.4.0.dev10, Hydra stores legacy instantiate target blocklists and related execution-policy collections in mutable module-level state. An attacker who controls multiple sibling target entries can resolve hydra._internal.target_policy.UNCONTROLLED_EXECUTION_TARGETS.discard through instantiate(), remove a denied target, and then invoke that target because sibling nodes are processed in insertion order against the same modified policy. The mutation persists in process-global state and can enable code execution with the application's privileges, while a narrow execution whitelist supplied by trusted Python code is not bypassed by the reported direct mutation path. This issue is fixed in versions 1.3.7 and 1.4.0.dev10.

Affected products

• Hydra-Ecosystem Hydra: from 1.3.4, before 1.3.7 (fixed in 1.3.7); from 1.4.0.dev4, before 1.4.0.dev10 (fixed in 1.4.0.dev10)

Published 2026-10-06. Last modified 2026-10-06.