---
title: "CVE-2026-63223: CodeIgniter: Uploaded file extension validation bypass in `is_image` and `mime_in` rules"
url: https://erroneo.us/security/cve/CVE-2026-63223/
description: "CVE-2026-63223 (codeigniter4/framework (Composer (PHP))): CodeIgniter is a PHP full-stack web framework. Prior to 4.7.4, the isimage and mimein upload…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-31
date_modified: 2026-08-07
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-63223"
kev: false
cvss: 9.8
epss: 0.008
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.8% , percentile 56: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 56% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes codeigniter4/framework (Composer (PHP)) < 4.7.4, fixed in 4.7.4 . Check your lockfile, including transitive dependencies.

## What it is

CodeIgniter is a PHP full-stack web framework. Prior to 4.7.4, the isimage and mimein 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 isimage or mimein without an independent safe extension check (such as extin 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.

## Affected packages

- Composer (PHP) `codeigniter4/framework` < 4.7.4 → fixed: 4.7.4

## Affected products (CVE record)

- codeigniter4 CodeIgniter4: < 4.7.4

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.80% probability of exploitation activity in the next 30 days; percentile 56.

## Sources

- [GitHub Advisory GHSA-mmj4-63m4-r6h5](https://github.com/advisories/GHSA-mmj4-63m4-r6h5)
- [CVE.org record CVE-2026-63223](https://www.cve.org/CVERecord?id=CVE-2026-63223)
- [NVD entry CVE-2026-63223](https://nvd.nist.gov/vuln/detail/CVE-2026-63223)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-mmj4-63m4-r6h5)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/commit/b6e9a4fa1dca2df3d3f261bdf61532df8c6420aa)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/releases/tag/v4.7.4)

---
Source page: https://erroneo.us/security/cve/CVE-2026-63223/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt