---
title: "CVE-2026-48062: CodeIgniter4 has a validation bypass when uploading file extensions via `ext_in` rule"
url: https://erroneo.us/security/cve/CVE-2026-48062/
description: "CVE-2026-48062 (codeigniter4/framework (Composer (PHP))): CodeIgniter is a PHP full-stack web framework. Prior to 4.7.3, the extin upload validation rule in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-17
date_modified: 2026-07-20
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-48062"
kev: false
cvss: 9.8
epss: 0.00775
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-48062: CodeIgniter4 has a validation bypass when uploading file extensions via `ext_in` rule

**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 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% 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)) < 4.7.2, fixed in 4.7.3 . Check your lockfile, including transitive dependencies.

## What it is

CodeIgniter is a PHP full-stack web framework. Prior to 4.7.3, the extin upload validation rule in system/Validation/StrictRules/FileRules.php checked the MIME-derived guessed extension instead of the client-provided filename extension. As a result, an uploaded file named shell.php containing GIF-like content could pass validation such as uploaded[avatar]|isimage[avatar]|mimein[avatar,image/gif]|extin[avatar,gif] because the detected MIME type maps to gif, even though the uploaded filename extension is php. Applications are impacted if they accept user-controlled uploads, rely on extin to validate the uploaded filename extension, save uploaded files using the original client filename with $file->move($path), store uploads in a web-accessible directory, and allow PHP or other executable files to run from that directory. In those conditions, this may lead to arbitrary code execution. This issue is fixed in version 4.7.3.

## Affected packages

- Composer (PHP) `codeigniter4/framework` < 4.7.2 → fixed: 4.7.3

## Affected products (CVE record)

- codeigniter4 CodeIgniter4: < 4.7.3

## 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): 0.78% probability of exploitation activity in the next 30 days; percentile 55.

## Sources

- [GitHub Advisory GHSA-2gr4-ppc7-7mhx](https://github.com/advisories/GHSA-2gr4-ppc7-7mhx)
- [CVE.org record CVE-2026-48062](https://www.cve.org/CVERecord?id=CVE-2026-48062)
- [NVD entry CVE-2026-48062](https://nvd.nist.gov/vuln/detail/CVE-2026-48062)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-2gr4-ppc7-7mhx)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/commit/29299349e7d232e9532767c7cefaed30957309be)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/releases/tag/v4.7.3)
- [codeigniter.com](https://codeigniter.com/user_guide/libraries/uploaded_files.html#moving-files)
- [codeigniter.com](https://codeigniter.com/user_guide/libraries/validation.html#rules-for-file-uploads)
- [github.com](https://github.com/codeigniter4/CodeIgniter4/blob/develop/CHANGELOG.md)

---
Source page: https://erroneo.us/security/cve/CVE-2026-48062/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt