CVE-2019-3881
HIGHCVE-2019-3881 is a high-severity (CVSS 7.8) CWE-427 vulnerability in bundler. O3 Security confirms whether CVE-2019-3881 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insecure path handling in Bundler
Blast Radius
bundlerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Bundler prior to 2.1.0 uses a predictable path in /tmp/, created with insecure permissions as a storage location for gems, if locations under the user's home directory are not available. If Bundler is used in a scenario where the user does not have a writable home directory, an attacker could place malicious code in this directory that would be later loaded and executed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | bundler | ≥ 1.14.0&&< 2.1.0 | 2.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bundler. 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 bundler to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-3881 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-2019-3881 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-2019-3881. 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-2019-3881 in your dependencies?
O3 detects CVE-2019-3881 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.