GHSA-qphc-hf5q-v8fc is a medium-severity (CVSS 6.1) Open Redirect vulnerability in actionpack. O3 Security confirms whether GHSA-qphc-hf5q-v8fc is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
actionpack Open Redirect in Host Authorization Middleware
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-qphc-hf5q-v8fc plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 365,017 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
actionpack💎actionpackReal-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
Specially crafted "X-Forwarded-Host" headers in combination with certain "allowed host" formats can cause the Host Authorization middleware in Action Pack to redirect users to a malicious website.
Impacted applications will have allowed hosts with a leading dot. For example, configuration files that look like this:
config.hosts << '.EXAMPLE.com'
When an allowed host contains a leading dot, a specially crafted Host header can be used to redirect to a malicious website.
This vulnerability is similar to CVE-2021-22881 and CVE-2021-22942.
Releases
The fixed releases are available at the normal locations.
Patches
To aid users who aren't able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.
- 6-0-host-authorzation-open-redirect.patch - Patch for 6.0 series
- 6-1-host-authorzation-open-redirect.patch - Patch for 6.1 series
- 7-0-host-authorzation-open-redirect.patch - Patch for 7.0 series
Please note that only the 6.1.Z, 6.0.Z, and 5.2.Z series are supported at present. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | actionpack | ≥ 6.0.0&&< 6.0.4.2 | 6.0.4.2 |
| 💎RubyGems | actionpack | ≥ 6.1.0&&< 6.1.4.2 | 6.1.4.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for actionpack. 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 actionpack to 6.0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qphc-hf5q-v8fc 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 GHSA-qphc-hf5q-v8fc 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 GHSA-qphc-hf5q-v8fc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-qphc-hf5q-v8fc in your dependencies?
O3 detects GHSA-qphc-hf5q-v8fc across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.