# CVE-2026-63223: CodeIgniter: Uploaded file extension validation bypass in is_image and mime_in rules

> Remote attackers can upload executable files if applications rely solely on is_image or mime_in validation and store files in web-accessible directories.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Jul 2026
- **Updated:** 31 Jul 2026
- **Also known as:** GHSA-mmj4-63m4-r6h5, UBUNTU-CVE-2026-63223

## What is CVE-2026-63223?

CVE-2026-63223 is a critical vulnerability in CodeIgniter4, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

CodeIgniter is a PHP full-stack web framework. Prior to 4.7.4, the is_image and mime_in upload validation rules do not independently enforce a safe client filename extension, allowing a remote attacker to upload executable content when an application preserves the client filename and stores uploads in a web-accessible script-enabled directory. Applications are impacted when they validate uploads using is_image or mime_in without an independent safe extension check (such as ext_in on patched versions), save uploaded files using the client-supplied filename, and place uploads in a web-accessible directory where PHP files can execute. This issue is fixed in version 4.7.4.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2026-63223?

2 open source packages ship an affected version, including codeigniter4/framework.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `codeigniter4/framework` | Packagist | All versions | 4.7.4 |
| `codeigniter4/framework` | Packagist | All versions | 4.7.4 |

## How do I fix CVE-2026-63223?

Upgrade codeigniter4/framework to 4.7.4 or later.

## Is CVE-2026-63223 being exploited?

There is no known exploitation of CVE-2026-63223 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-63223 PoC — CodeIgniter 4 is_image/mime_in File Upload RCE (CVSS 9.8). Unauthenticated remote code execution via unrestricted file upload bypass using image magic bytes. Fixed in v4.7.4. (github_poc): https://github.com/imbas007/CVE-2026-63223-POC
- CVE-2026-63223 — CI4RCE: CodeIgniter 4 is_image/mime_in File Upload RCE. Magic bytes bypass (getExtension vs getClientExtension). CVSS 9.8 | CWE-434 | CI4 < 4.7.4 (github_poc): https://github.com/shinthink/CVE-2026-63223
- https://github.com/myeongji1/cve-2026-63223-ctf (github_poc): https://github.com/myeongji1/cve-2026-63223-ctf

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63223 and fix it if it is affected.

What it is: CVE-2026-63223 is a critical vulnerability in CodeIgniter4, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-63223 in the wild and no public exploit code.

Affected packages and fixed versions:
- codeigniter4/framework (Packagist): affected all versions; fixed in 4.7.4
- codeigniter4/framework (Packagist): affected all versions; fixed in 4.7.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63223/ (Markdown: https://insights.sbomify.com/CVE-2026-63223/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63223
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63223
- OSV: https://osv.dev/vulnerability/CVE-2026-63223

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63223/
Summaries are generated and may contain mistakes; the official description above is the record.