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.
Blast Radius
phoenix💧phoenix💧phoenixReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
The Phoenix team designed Phoenix.Controller.redirect/2 to protect against redirects allowing user input to redirect to an external URL where your application code otherwise assumes a local path redirect. This is why the :to option is used for “local” URL redirects and why you must pass the :external option to intentionally allow external URLs to be redirected to. It has been disclosed that carefully crafted user input may be treated by some browsers as an external URL. An attacker can use this vulnerability to aid in social engineering attacks. The most common use would be to create highly believable phishing attacks. For example, the following user input would pass local URL validation, but be treated by Chrome and Firefox as external URLs:
http://localhost:4000/?redirect=/\nexample.com
Not all browsers are affected, but latest Chrome and Firefox will issue a get request for example.com and successfully redirect externally
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | phoenix | all versions | 1.0.6 |
| 💧Hex | phoenix | ≥ 1.1.0&&< 1.1.8 | 1.1.8 |
| 💧Hex | phoenix | ≥ 1.2.0&&< 1.2.3 | 1.2.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phoenix. 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 phoenix to 1.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cmfh-8f8r-fj96 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-cmfh-8f8r-fj96 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-cmfh-8f8r-fj96. 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-cmfh-8f8r-fj96 in your dependencies?
O3 detects GHSA-cmfh-8f8r-fj96 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.