CVE-2026-34587
CVE-2026-34587 is a security vulnerability in getkirby/cms. O3 Security confirms whether CVE-2026-34587 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kirby has Server-Side Template Injection (SSTI) via double template resolution in option rendering
Real-World Exposure
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
Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, Kirby's user permissions control which user role is allowed to perform specific actions to content models in the CMS. These permissions are defined for each role in the user blueprint (site/blueprints/users/...). It is also possible to customize the permissions for each target model in the model blueprints (such as in site/blueprints/pages/...) using the options feature. The permissions and options together control the authorization of user actions. For pages, Kirby provides the pages.create and pages.changeStatus permissions (among others). In affected releases, Kirby checked these permissions independently and only for the respective action. However the changeStatus permission didn't take effect on page creation. New pages are created as drafts by default and need to be published by changing the page status of an existing page draft. This is ensured when the page is created via the Kirby Panel. However the REST API allows to override the isDraft flag when creating a new page. This allowed authenticated attackers with the pages.create permission to immediately create published pages, bypassing the normal editorial workflow. The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. Kirby has updated the Options logic to no longer double-resolve queries in option values coming from OptionsQuery or OptionsApi sources. Kirby now only resolves queries that are directly configured in the blueprints.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 4.9.0 |
| 🐘Packagist | getkirby/cms | ≥ 5.0.0&&< 5.4.0 | 5.4.0 |
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 4.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34587 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-2026-34587 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-2026-34587. 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-2026-34587 in your dependencies?
O3 detects CVE-2026-34587 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.