CVE-2026-106442
HighCVSS 7.8Summary
Hydra from 1.3.4 until 1.3.6 and 1.4.0.dev9 has an incomplete target blacklist for instantiate() that does not fully check the effective callable selected by the target field. Execution wrappers such as timeit.timeit, pickle.loads, aliases, callable-returning helpers, generic dispatch, and deferred calls can obscure or defer the effective target and bypass name-based authorization.
Risk Assessment
An attacker who controls untrusted Hydra configuration can execute code with the application's privileges, potentially leading to application or system compromise.
Recommendation
Upgrade Hydra to version 1.3.6 or 1.4.0.dev9 (or later) and avoid processing untrusted configurations.
Other vulnerabilities in Hydra
See all- CVE-2026-106441High
Hydra prior to 1.3.6 and 1.4.0.dev9 passes Python logging configuration to logging.config.dictConfig() without applying Hydra's target policy to handler class values or formatter, filter, handler, queue, and listener factories. An attacker who controls Hydra logging configuration can select an importable class or factory and cause it to be invoked with the application's privileges.
- CVE-2026-106440High
Hydra from 1.2.0 until 1.3.0 and 1.4.0.dev10 in the hydra-optuna-sweeper package accepts a configuration-controlled dotted path in hydra.sweeper.custom_search_space, resolves it with hydra.utils.get_method(), and later invokes the returned callable in the Hydra controller process. Because get_method() does not apply the execution policy used by instantiate(), an attacker who controls Optuna sweep configuration or command-line overrides can select importable Python code for execution with the application's privileges.
- CVE-2026-106439High
Hydra from 1.3.4 until 1.3.7 and 1.4.0.dev10 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.
- CVE-2026-68508High
Hydra before version 1.3.4 has an arbitrary code execution vulnerability. The hydra.utils.instantiate() function resolves and calls Python objects selected by configuration, allowing an attacker to invoke dangerous callables.
- CVE-2026-56766High
A stack buffer overflow vulnerability in Hydra through version 9.7 (fixed in commit 9cc84c2) affects NTLM authentication in SMTP, POP3, IMAP, NNTP, HTTP, HTTP-Proxy, and HTTP-Proxy-Urlenum modules when processing malicious NTLM Type-2 challenges. A remote server can send a crafted challenge with an excessively long domain string, causing base64-encoded response data to overflow a 500-byte stack buffer by 18 to 330 bytes, enabling remote code execution on systems without stack protection.
Original NVD description (English source)
Hydra is a framework for elegantly configuring complex applications. From 1.3.4 until 1.3.6 and 1.4.0.dev9, the instantiate() target blacklist introduced for CVE-2026-68508 incompletely checks the effective callable selected by the target field. Execution wrappers such as timeit.timeit, executable deserialization through pickle.loads, aliases, callable-returning helpers, generic dispatch, and deferred calls can obscure or defer the effective target and bypass name-based authorization. An attacker who causes an application to instantiate untrusted Hydra configuration can use these gaps to execute code with the application's privileges. This issue is fixed in versions 1.3.6 and 1.4.0.dev9.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS