Summary
Hydra instantiate target blacklist bypasses permit code execution
Hydra's instantiate() API resolves and invokes Python callables named by the _target_ field in configuration. The target blacklist introduced for CVE-2026-68508 was incomplete.
Representative bypasses included execution wrappers such as timeit.timeit, executable deserialization through pickle.loads, and generic dispatch or wrapper targets that obscured the effective callable. Target aliases, callable-returning helpers, and deferred dispatch could similarly bypass name-based checks.
An attacker who can cause an application to instantiate an untrusted Hydra configuration can use these gaps to execute code with the application's privileges.
Remediation
Upgrade to Hydra 1.3.6, or to Hydra 1.4.0.dev9 or later when testing the 1.4 prerelease line.
On Hydra 1.3, do not instantiate configuration from untrusted sources. On Hydra 1.4 and later, constrain untrusted configuration with a narrow execution whitelist supplied by trusted Python code.
For Hydra 1.4 execution-whitelist configuration, see: https://hydra.cc/docs/advanced/execution_whitelist/
Impact
CVE-2026-106442 has a CVSS score of 7.8 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.3.6, 1.4.0.dev9); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Hydra 1.3.6 expands and hardens the blacklist used by the 1.3 compatibility line. It blocks the reported execution and deserialization surfaces, checks canonical callable identities and aliases, mediates callable results, and blocks generic dispatch and wrapper targets that bypass immediate target checks.
The Hydra 1.3 blacklist is a best-effort, defense-in-depth measure. It is not a complete security boundary and does not make untrusted configuration safe to instantiate.
Hydra 1.4.0.dev9 applies the same hardening and introduces the execution whitelist as the recommended primary security boundary. When a whitelist is supplied, targets are rejected unless trusted Python code authorizes them. If no whitelist is supplied, Hydra preserves legacy behavior with a deprecation warning and the blacklist as a best-effort compatibility fallback. Targets that permit configuration to select or supply executable behavior remain non-whitelistable.
Frequently Asked Questions
- What is CVE-2026-106442? CVE-2026-106442 is a high-severity security vulnerability in hydra-core (pip), affecting versions >= 1.3.4, < 1.3.6. It is fixed in 1.3.6, 1.4.0.dev9.
- How severe is CVE-2026-106442? CVE-2026-106442 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of hydra-core are affected by CVE-2026-106442? hydra-core (pip) versions >= 1.3.4, < 1.3.6 is affected.
- Is there a fix for CVE-2026-106442? Yes. CVE-2026-106442 is fixed in 1.3.6, 1.4.0.dev9. Upgrade to this version or later.
- Is CVE-2026-106442 exploitable, and should I be worried? Whether CVE-2026-106442 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-106442 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-106442?
- Upgrade
hydra-coreto 1.3.6 or later - Upgrade
hydra-coreto 1.4.0.dev9 or later
- Upgrade