# CVE-2026-87930: MaxSite CMS through 109.6 PHP Object Injection via ci_session

> Unauthenticated attackers can achieve code execution or corrupt state in MaxSite CMS by injecting PHP objects via forged session cookies using a hardcoded key.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-2phq-cm26-22pm

## What is CVE-2026-87930?

CVE-2026-87930 is a critical unsafe deserialization vulnerability in MaxSite CMS, published on 9 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

MaxSite CMS through 109.6 passes the ci_session cookie to unserialize() without class restrictions, allowing unauthenticated attackers to inject PHP objects. Attackers can forge valid session cookies using the hardcoded encryption key to trigger magic methods and corrupt application state or achieve code execution if gadget classes exist.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-87930?


## How do I fix CVE-2026-87930?

No fix has been published for CVE-2026-87930 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-87930 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87930 exists.

Public exploit code:

- CVE-2026-87930 Joomla Multi-CVE RCE suite — authorized testing only (github_poc): https://github.com/winrarzipsexploit/CVE-2026-87930

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87930 and fix it if it is affected.

What it is: CVE-2026-87930 is a critical unsafe deserialization vulnerability in MaxSite CMS, published on 9 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87930 exists.

Affected product: MaxSite CMS. 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-2026-87930/ (Markdown: https://insights.sbomify.com/CVE-2026-87930/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87930
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87930
- OSV: https://osv.dev/vulnerability/CVE-2026-87930

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87930/
Summaries are generated and may contain mistakes; the official description above is the record.