CVE-2015-3900
CVE-2015-3900 is a CWE-254 vulnerability in rubygems-update. O3 Security confirms whether CVE-2015-3900 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
RubyGems vulnerable to DNS hijack attack
Blast Radius
rubygems-update💎rubygems-update💎rubygems-updateReal-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
RubyGems 2.0.x before 2.0.16, 2.2.x before 2.2.4, and 2.4.x before 2.4.7 does not validate the hostname when fetching gems or making API requests, which allows remote attackers to redirect requests to arbitrary domains via a crafted DNS SRV record, aka a "DNS hijack attack."
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rubygems-update | ≥ 2.0.0&&< 2.0.16 | 2.0.16 |
| 💎RubyGems | rubygems-update | ≥ 2.2.0&&< 2.2.4 | 2.2.4 |
| 💎RubyGems | rubygems-update | ≥ 2.4.0&&< 2.4.7 | 2.4.7 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rubygems-update. 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 rubygems-update to 2.0.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2015-3900 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-2015-3900 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-2015-3900. 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-2015-3900 in your dependencies?
O3 detects CVE-2015-3900 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.