CVE-2021-43805
HIGHReDos vulnerability on guest checkout email validation
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
solidus_core💎solidus_core💎solidus_coreReal-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
Solidus is a free, open-source ecommerce platform built on Rails. Versions of Solidus prior to 3.1.4, 3.0.4, and 2.11.13 have a denial of service vulnerability that could be exploited during a guest checkout. The regular expression used to validate a guest order's email was subject to exponential backtracking through a fragment like a.a. Versions 3.1.4, 3.0.4, and 2.11.13 have been patched to use a different regular expression. The maintainers added a check for email addresses that are no longer valid that will print information about any affected orders that exist. If a prompt upgrade is not an option, a workaround is available. It is possible to edit the file config/application.rb manually (with code provided by the maintainers in the GitHub Security Advisory) to check email validity.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | solidus_core | all versions | 2.11.13 |
| 💎RubyGems | solidus_core | ≥ 3.0.0&&< 3.0.4 | 3.0.4 |
| 💎RubyGems | solidus_core | ≥ 3.1.0&&< 3.1.4 | 3.1.4 |
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 solidus_core. 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 solidus_core to 2.11.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43805 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-2021-43805 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-2021-43805. 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-2021-43805 in your dependencies?
O3 detects CVE-2021-43805 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.