CVE-2025-4166
MEDIUMCVE-2025-4166 is a medium-severity (CVSS 4.5) CWE-209 vulnerability in github.com/hashicorp/vault. O3 Security confirms whether CVE-2025-4166 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vault May Include Sensitive Data in Error Logs When Using the KV v2 Plugin
Blast Radius
github.com/hashicorp/vaultReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Vault Community and Vault Enterprise Key/Value (kv) Version 2 plugin may unintentionally expose sensitive information in server and audit logs when users submit malformed payloads during secret creation or update operations via the Vault REST API. This vulnerability, identified as CVE-2025-4166, is fixed in Vault Community 1.19.3 and Vault Enterprise 1.19.3, 1.18.9, 1.17.16, 1.16.20.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/hashicorp/vault | ≥ 0.3.0&&< 1.19.3 | 1.19.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/hashicorp/vault. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/hashicorp/vault to 1.19.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-4166 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-4166 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-4166. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-4166 in your dependencies?
O3 detects CVE-2025-4166 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.