CVE-2026-63223 is a critical-severity (CVSS 9.8) Unrestricted File Upload vulnerability in codeigniter4/framework. 1 public exploit reference exists, so weaponization risk is real. A fix is available for codeigniter4/framework — see the affected versions and patch details below.
CodeIgniter: Uploaded file extension validation bypass in is_image and mime_in rules
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-63223.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-63223 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 389,824 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
codeigniter4/frameworkReal-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
Impact
This is an unsafe file upload validation vulnerability that can lead to remote code execution in vulnerable application configurations.
Applications are impacted when they:
- validate uploads using
is_imageormime_inwithout an independent safe extension check, such asext_inon patched versions - save uploaded files using the client-supplied filename
- place uploads in a web-accessible directory where PHP files can execute
Patches
Upgrade to v4.7.4 or later.
Workarounds
- Save uploads outside the public web root, preferably under
writable/uploads. - Use
$file->store()or$file->move($path, $file->getRandomName())instead of preserving the original client filename. - Disable script execution in any public upload directory.
- Manually verify the client filename extension before moving the file.
- For image uploads, reject files when
$file->getClientExtension()is not an allowed image extension. - For exact MIME-type validation, reject files when
$file->getClientExtension()does not match$file->guessExtension().
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | codeigniter4/framework | all versions | 4.7.4composer require codeigniter4/framework:^4.7.4 |
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 codeigniter4/framework, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update codeigniter4/framework to 4.7.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-63223 is resolved across your whole dependency graph.
Workarounds
Treat uploaded files as untrusted until proven otherwise: validate the actual content type rather than the supplied extension, store uploads outside the web root on a volume mounted without execute permission, and rename them to server-generated identifiers so an attacker cannot choose the path a request will later resolve.
Frequently Asked Questions
Is CVE-2026-63223 in your dependencies?
Find it across Packagist, including transitive dependencies.