Hydra core: Hydra legacy target blacklist permits unsafe PyYAML loading
Affects hydra-coreSource GCVE Database
CVSS 7.8 High : upgrade to 1.3.8 soon.
Data as of 27 Oct 2026, 18:29 UTC
- Patch
- Available – fixed in 1.3.8, 1.4.0rc3
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HWhat to do
Upgrade hydra-core to 1.3.8; hydra-core to 1.4.0rc3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| PyPIhydra-core | Affected
| Fixed in
|
| PyPIhydra-core | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in hydra-core versions 1.3.8 and 1.4.0rc3 that blocks unsafe yaml targets except for safe_load and safe_dump functions. Users should upgrade to these fixed versions. As a workaround, do not pass untrusted configuration to instantiate() or call(), and for Hydra 1.4, use a narrow execution whitelist from trusted Python code. Do not allow untrusted configuration to select execution policies or opt out of checks.
Description
Hydra core versions 1.3.6 through 1.3.7 and 1.4.0.dev9 through 1.4.0rc2 have a vulnerability in the legacy target blacklist that omits unsafe PyYAML loading functions. This allows an attacker who controls the target and arguments passed to instantiate() to execute arbitrary Python code via a malicious YAML configuration. The issue affects legacy no-whitelist paths and is not a bypass of Hydra 1.4's execution whitelist. The vulnerability is fixed in versions 1.3.8 and 1.4.0rc3.
References
- github.com/hydra-ecosystem/hydra/security/advisories/GHSA-757g-8w3h-hp29 (opens in a new tab)
- github.com/hydra-ecosystem/hydra/commit/9a7a9a287d565311183da3392bee4345a7fab6d7 (opens in a new tab)
- github.com/hydra-ecosystem/hydra/commit/de5554320c17cd2d974492c03d0b1456adb4a8ef (opens in a new tab)
- github.com/hydra-ecosystem/hydra (opens in a new tab)
- github.com/hydra-ecosystem/hydra/releases/tag/v1.3.8 (opens in a new tab)
- github.com/hydra-ecosystem/hydra/releases/tag/v1.4.0rc3 (opens in a new tab)