CVE-2025-58759 is a medium-severity vulnerability affecting the TinyEnv PHP library versions 1.0.9 and 1.0.10. TinyEnv is a utility used to load environment variables from .env files into PHP applications. The vulnerability arises from improper input validation (CWE-20) where TinyEnv fails to correctly strip inline comments within environment variable values. Specifically, if a .env file contains inline comments (e.g., using the '#' character), TinyEnv does not remove these comments from the variable values, causing the loaded environment variables to include unintended characters or comment text. This can lead to unexpected application behavior, such as logic errors, insecure default configurations, or even authentication failures if environment variables are used for security-sensitive settings like credentials or feature flags. The vulnerability does not allow remote exploitation without local access (CVSS vector AV:L), requires low attack complexity, and no privileges or user interaction. The impact is limited to confidentiality and integrity, with no availability impact. The issue is resolved in TinyEnv version 1.0.11. Until upgrading, users should avoid inline comments in .env files or sanitize environment variables after loading to prevent misconfiguration or security issues. No known exploits are currently reported in the wild.

For European organizations, this vulnerability poses a risk primarily to PHP applications that rely on TinyEnv versions 1.0.9 or 1.0.10 for environment variable management. Misconfigured environment variables can lead to logic errors or insecure defaults, potentially exposing sensitive data or weakening authentication mechanisms. This could result in unauthorized access to application features or data leakage. Although the vulnerability requires local access to modify .env files or deploy malicious environment configurations, insider threats or compromised deployment pipelines could exploit this flaw. Organizations with strict compliance requirements, such as GDPR, may face regulatory risks if sensitive data confidentiality is compromised. The impact is more pronounced in sectors heavily reliant on PHP applications with environment-based configuration, including finance, healthcare, and e-commerce within Europe.

1. Upgrade TinyEnv to version 1.0.11 or later immediately to apply the official fix. 2. Audit all .env files to remove inline comments or avoid using inline comments altogether until the patch is applied. 3. Implement manual sanitization of environment variable values after loading to strip any unintended comment characters or trailing text. 4. Restrict write access to .env files to trusted personnel and secure deployment pipelines to prevent unauthorized modifications. 5. Incorporate environment variable validation checks in application startup routines to detect malformed or suspicious values. 6. Monitor application logs for anomalies related to configuration or authentication failures that may indicate exploitation attempts. 7. Educate development and operations teams about the risks of inline comments in .env files and secure environment management best practices.