GHSA-43qq-qw4x-28f8
MEDIUMKirby CMS vulnerable to user enumeration in the code-based login and password reset forms
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
getkirby/cms🐘getkirby/cms🐘getkirby/cms🐘getkirby/cmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
TL;DR
This vulnerability only affects you if you are using the code or password-reset auth method with the auth.methods option. It can only be successfully exploited under server configuration conditions outside of the attacker's control.
Introduction
User enumeration is a type of vulnerability that allows attackers to confirm which users are registered in a Kirby installation. This information can be abused for social engineering attacks against users of the site or to find out the organizational structure of the company.
User enumeration attacks are performed by entering an existing and a non-existing user into the email address field of the login form. If the system returns a different response or behaves differently depending on whether the user exists, the attacker can enter unknown email addresses and use the different behavior as a clue for the (non-)existing user.
Impact
Under normal circumstances, entering an invalid email address results in a "fake" login code form that looks exactly like the one of an existing user (unless debugging is enabled). However, the code that handles the creation of a code challenge (for code-based login or password reset) didn't catch errors that occurred while the challenge request was processed:
- If the challenge itself runs into an error (e.g. if the email could not be sent), attackers could tell existing users (where the challenge code is called) from non-existing users (where the challenge code is not called and therefore does not output an error).
- If you are using the
user.login:failedhook and any exception is thrown within the hook, attackers could see that the user does not exist.
As long as no error occurs during challenge creation and during the processing of the user.login:failed hook, your Kirby sites are not affected by this vulnerability.
Patches
The problems have been patched in Kirby 3.5.8.2, Kirby 3.6.6.2, Kirby 3.7.5.1 and Kirby 3.8.1. Please update to one of these or a later version to fix the vulnerability.
All of the mentioned releases contain two patches for this vulnerability:
- All errors that occur during the creation of an auth challenge (code-based login or password reset) are swallowed by the backend and only displayed to the user if debugging is enabled.
- We added a new
auth.debugoption that can be enabled separately from thedebugoption. If disabled, auth errors are only printed to the PHP error log. This ensures that security-critical errors are only displayed if they are really necessary for debugging.
Workarounds
We recommend to update to one of the patch releases. If you cannot update immediately, you can work around the issue by setting the auth.methods option to password, which disables the code-based login and password reset forms.
However please note that your site will still be vulnerable against another user enumeration issue that was also fixed in the same patch releases.
Credits
Thanks to Florian Merz (@florianmrz) of hatchery.io for responsibly reporting the identified issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | ≥ 3.5.0&&< 3.5.8.2 | 3.5.8.2 |
| 🐘Packagist | getkirby/cms | ≥ 3.6.0&&< 3.6.6.2 | 3.6.6.2 |
| 🐘Packagist | getkirby/cms | ≥ 3.7.0&&< 3.7.5.1 | 3.7.5.1 |
| 🐘Packagist | getkirby/cms | ≥ 3.8.0&&< 3.8.1 | 3.8.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms. 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 getkirby/cms to 3.5.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-43qq-qw4x-28f8 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-43qq-qw4x-28f8 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-43qq-qw4x-28f8. 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-43qq-qw4x-28f8 in your dependencies?
O3 detects GHSA-43qq-qw4x-28f8 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.