# CVE-2026-54611: InstantCMS has Remote Code Execution in package installer

> Authenticated attackers can achieve remote code execution in InstantCMS by uploading malicious components and custom .htaccess files to bypass execution restrictions.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 9 Sep 2026
- **Also known as:** GHSA-vvgv-h28h-p2m5

## What is CVE-2026-54611?

CVE-2026-54611 is a medium-severity vulnerability in instantsoft icms2, published on 8 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

InstantCMS is a free and open source content management system. Versions prior to 2.18.2 have a Remote Code Execution (RCE) issue that allows remote authenticated attackers to execute any PHP code via the component installer. It is possible to upload a malicious component into the server, however, it won't be installed, but upload files will be executed. Normally all php files in upload folder are not executed, however, by uploading custom .htaccess it becomes possible. Version 2.18.2 contains a fix.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2026-54611?


## How do I fix CVE-2026-54611?

No fix has been published for CVE-2026-54611 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-54611 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54611 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54611 and fix it if it is affected.

What it is: CVE-2026-54611 is a medium-severity vulnerability in instantsoft icms2, published on 8 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54611 exists.

Affected product: instantsoft icms2. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-54611/ (Markdown: https://insights.sbomify.com/CVE-2026-54611/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54611
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54611
- OSV: https://osv.dev/vulnerability/CVE-2026-54611

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54611/
Summaries are generated and may contain mistakes; the official description above is the record.