# CVE-2026-81891: elFinder: ZIP extraction bypasses uploadDeny MIME filter allowing PHP file upload (RCE)

> Attackers can bypass MIME filters to upload and execute PHP files via ZIP extraction, leading to remote code execution.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/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 Aug 2026
- **Updated:** 1 Sep 2026
- **Also known as:** GHSA-gxmj-r5rf-ggwq

## What is CVE-2026-81891?

CVE-2026-81891 is a high-severity vulnerability in Studio-42 elFinder, published on 31 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

elFinder is an open-source file manager for web, written in JavaScript using jQuery UI. Prior to 2.1.70, checkExtractItems() in php/elFinderVolumeDriver.class.php calls mimetypeInternalDetect() without passing the result through mimeTypeNormalize(). Because the .phtml, .phar, .php5, and .php3 extensions are absent from mime.types, the staticMimeMap entries that map them to text/x-php are not applied, and allowPutMime() permits extraction even when uploadDeny blocks text/x-php. An attacker with ZIP upload permission can extract PHP-executable files into a web-accessible files/ directory and achieve remote code execution when the server executes those extensions. This issue is fixed in version 2.1.70.

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

## Which versions are affected by CVE-2026-81891?

2 open source packages ship an affected version, including Studio-42/elFinder.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Studio-42/elFinder` | Packagist | All versions | 2.1.70 |
| `Studio-42/elFinder` | Packagist | All versions | 2.1.70 |

## How do I fix CVE-2026-81891?

Upgrade Studio-42/elFinder to 2.1.70 or later.

## Is CVE-2026-81891 being exploited?

There is no known exploitation of CVE-2026-81891 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81891 and fix it if it is affected.

What it is: CVE-2026-81891 is a high-severity vulnerability in Studio-42 elFinder, published on 31 Aug 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-2026-81891 in the wild and no public exploit code.

Affected packages and fixed versions:
- Studio-42/elFinder (Packagist): affected all versions; fixed in 2.1.70
- Studio-42/elFinder (Packagist): affected all versions; fixed in 2.1.70

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-2026-81891/ (Markdown: https://insights.sbomify.com/CVE-2026-81891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81891
- OSV: https://osv.dev/vulnerability/CVE-2026-81891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81891/
Summaries are generated and may contain mistakes; the official description above is the record.