CVE-2025-58759 Overview
CVE-2025-58759 is an input validation vulnerability [CWE-20] in TinyEnv, an environment variable loader for PHP applications. Versions 1.0.9 and 1.0.10 fail to strip inline comments inside .env values. Loaded variables retain unintended characters, including # and any comment text that follows. Applications that rely on strict environment values can encounter logic errors, insecure defaults, or authentication failures. The vendor datahihi1 fixed the issue in version 1.0.11.
Critical Impact
Misparsed .env values can propagate malformed configuration into security-sensitive code paths, resulting in weakened authentication logic and unintended runtime behavior in dependent PHP applications.
Affected Products
- datahihi1 TinyEnv version 1.0.9
- datahihi1 TinyEnv version 1.0.10
- PHP applications consuming environment variables through TinyEnv
Discovery Timeline
- 2025-09-09 - CVE-2025-58759 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-58759
Vulnerability Analysis
TinyEnv parses .env files and exposes key-value pairs to PHP applications through the environment. The parser in versions 1.0.9 and 1.0.10 does not remove inline comment sequences from the value portion of a line. A line such as API_KEY=secret # production key yields a value containing the trailing # marker and comment text rather than the intended token.
Downstream code that compares, hashes, or forwards these values receives corrupted data. Authentication routines that expect exact matches fail or fall back to defaults. Feature flags and toggles evaluate against unexpected strings. Configuration values passed to external services carry embedded comment text, which can break integrations or produce logic errors that weaken security posture.
The flaw is classified as Improper Input Validation [CWE-20]. The exposure impacts confidentiality and integrity where environment values feed into access decisions, secret handling, or conditional security logic.
Root Cause
The TinyEnv value parser treats the entire right-hand side of the KEY=VALUE assignment as literal content. It does not tokenize on unescaped # characters that follow whitespace, which is the conventional inline comment delimiter for .env files. Values therefore retain trailing comment sequences instead of the intended data.
Attack Vector
An attacker who controls or influences the content of a .env file, such as through a supply chain intrusion, a misconfigured deployment pipeline, or a shared configuration template, can inject comment sequences that alter effective configuration. In deployments where .env files are generated from templated sources, unintended characters can also reach production without malicious intent, producing exploitable weaknesses in authentication or authorization logic.
The vulnerability is exploitable through the configuration surface rather than through direct network interaction with TinyEnv itself. Impact depends on how the consuming PHP application uses the loaded values. See the GitHub Security Advisory for vendor details.
Detection Methods for CVE-2025-58759
Indicators of Compromise
- Environment variables at runtime containing trailing # characters or unexpected comment text.
- Authentication or authorization failures correlated with .env files that use inline comments.
- Application logs showing configuration values with unexpected whitespace or appended tokens.
Detection Strategies
- Inventory PHP projects for the datahihi1/tiny-env Composer dependency and flag versions 1.0.9 and 1.0.10.
- Statically scan .env files across repositories and deployment artifacts for lines containing = followed by a value and an inline # comment.
- Add runtime assertions or unit tests that verify parsed environment values do not contain # when strict values are expected.
Monitoring Recommendations
- Alert on dependency manifests (composer.json, composer.lock) that pin vulnerable TinyEnv versions.
- Track configuration drift in .env files across environments to detect introduction of inline comments.
- Log and review authentication anomalies that may indicate malformed secrets loaded from environment variables.
How to Mitigate CVE-2025-58759
Immediate Actions Required
- Upgrade TinyEnv to version 1.0.11 or later in all PHP applications.
- Audit .env files for inline comments and move comments to their own lines.
- Rotate secrets whose values may have been truncated or malformed by the flawed parser.
Patch Information
The maintainer released the fix in TinyEnv 1.0.11. Update the dependency via Composer using composer require datahihi1/tiny-env:^1.0.11 and redeploy affected applications. Refer to the GitHub Security Advisory GHSA-72cm-7236-h43r for the vendor's disclosure.
Workarounds
- Avoid inline comments inside .env files; place comments on separate lines prefixed with #.
- Sanitize loaded values manually in application code by trimming trailing #-delimited content before use.
- Enforce configuration linting in CI to reject .env files that contain inline comment syntax on value lines.
# Configuration example: upgrade TinyEnv and validate environment values
composer require datahihi1/tiny-env:^1.0.11
composer update datahihi1/tiny-env
# Lint .env files for inline comments before deployment
grep -nE '^[A-Za-z_][A-Za-z0-9_]*=.*[[:space:]]#' .env && \
echo 'Inline comment detected in .env - move comment to its own line' && exit 1
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
