Snyk agent scan: pydantic-settings: NestedSecretsSettingsSource follows symlinks outside secrets_dir, enabling local file read and bypassing secrets_dir_max_size (CVE-2026-58203)

The NestedSecretsSettingsSource component in pydantic-settings reads secret values from files in a configured secrets_dir. When secrets_nested_subdir=True, it follows symbolic links inside secrets_dir that point outside, allowing files outside the directory to be read into settings values. The size check uses Path.glob which does not follow symlinks, while the loader uses glob.iglob which does, causing inconsistent size accounting and bypass of the secrets_dir_max_size limit. This enables unintended local file reads and resource usage amplification via cyclic symlinks. Exploitation requires the ability to place symlinks inside the secrets_dir. The vulnerability is patched in pydantic-settings 2.14.2, which enforces strict directory traversal within secrets_dir and consistent size checks.

An attacker or lower-privileged component able to place symbolic links inside the configured secrets_dir can cause the application to read files outside the intended directory into settings values, violating confidentiality. Additionally, the secrets_dir_max_size limit can be bypassed, potentially leading to resource exhaustion. The vulnerability does not enable remote exploitation by itself and requires local or privileged access to influence the secrets directory contents.

Upgrade to pydantic-settings version 2.14.2 or later, which fixes the vulnerability by restricting directory traversal to within the secrets_dir, using a single cycle-safe iterator for size checks and loading, and skipping files whose resolved paths escape the secrets_dir. If upgrading is not possible immediately, ensure the secrets_dir is fully controlled by the application with no writable or attacker-influenced entries, or disable secrets_nested_subdir=True.