CVE-2026-45368
CVE-2026-45368 is a Cross-site Scripting (XSS) vulnerability in getkirby/cms. O3 Security confirms whether CVE-2026-45368 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kirby: Cross-site scripting (XSS) from links in KirbyTags and image blocks in the site frontend
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45368.
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.
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. In versions prior to 4.9.1 and 5.4.1, the underlying URL methods for the KirbyTags and image blocks components did not filter out malicious URL values that resolve to script execution. The vulnerability affects four first-party Kirby renderers that produce <a href="…"> output from editor-supplied field values: the (link: …) KirbyTag, the link: parameter of the (image: …) KirbyTag when it does not resolve to a known file or self, the link field of the built-in image block, and the HTML importer for the blocks field (which accepted the same malicious input as the image block link field). While simple avascript: URLs were already deactivated by treating them as a relative path and prepending a single slash to the URL, the use of URLs of the format javascript://x%0A… bypasses this protection. The vbscript:, data:, livescript:, mocha: and jar: schemes are affected by the same underlying gap. This issue has been fixed in versions 4.9.1 and 5.4.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 4.9.1 |
| 🐘Packagist | getkirby/cms | ≥ 5.0.0&&< 5.4.1 | 5.4.1 |
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 4.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45368 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-2026-45368 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-2026-45368. 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-2026-45368 in your dependencies?
O3 detects CVE-2026-45368 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.