GHSA-8727-m6gj-mc37
HIGHGHSA-8727-m6gj-mc37 is a high-severity (CVSS 7.5) Deserialization of Untrusted Data vulnerability in actionpack. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-8727-m6gj-mc37 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Possible Strong Parameters Bypass in ActionPack
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
There is a strong parameters bypass vector in ActionPack.
Versions Affected: rails <= 6.0.3 Not affected: rails < 5.0.0 Fixed Versions: rails >= 5.2.4.3, rails >= 6.0.3.1
Impact
In some cases user supplied information can be inadvertently leaked from
Strong Parameters. Specifically the return value of each, or each_value,
or each_pair will return the underlying "untrusted" hash of data that was
read from the parameters. Applications that use this return value may be
inadvertently use untrusted user input.
Impacted code will look something like this:
def update
# Attacker has included the parameter: `{ is_admin: true }`
User.update(clean_up_params)
end
def clean_up_params
params.each { |k, v| SomeModel.check(v) if k == :name }
end
Note the mistaken use of each in the clean_up_params method in the above
example.
Workarounds
Do not use the return values of each, each_value, or each_pair in your
application.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | actionpack | ≥ 5.0.0&&< 5.2.4.3 | 5.2.4.3 |
| 💎RubyGems | actionpack | ≥ 6.0.0&&< 6.0.3.1 | 6.0.3.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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 5.2.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8727-m6gj-mc37 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-8727-m6gj-mc37 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-8727-m6gj-mc37. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat CloudForms and Red Hat Satellite ship affected RubyGem actionpack and uses strong parameters, however, products are not vulnerable since safe return values are used in product code.
Frequently Asked Questions
Is GHSA-8727-m6gj-mc37 in your dependencies?
O3 detects GHSA-8727-m6gj-mc37 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.