# CVE-2026-41670: Admidio: SAML Response Sent to Unvalidated Assertion Consumer Service URL from AuthnRequest

> Attackers can redirect SAML responses to malicious URLs, exposing user identity data and enabling account takeover in Admidio.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 7 May 2026
- **Updated:** 7 May 2026
- **Also known as:** GHSA-p9w9-87c8-m235

## What is CVE-2026-41670?

CVE-2026-41670 is a high-severity vulnerability in admidio, published on 7 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Admidio is an open-source user management solution. Prior to version 5.0.9, the SAML IdP implementation in Admidio's SSO module uses the AssertionConsumerServiceURL value directly from incoming SAML AuthnRequest messages as the destination for the SAML response, without validating it against the registered ACS URL (smc_acs_url) stored in the database for the corresponding service provider client. An attacker who knows the Entity ID of a registered SP client can craft a SAML AuthnRequest with an arbitrary AssertionConsumerServiceURL, causing the IdP to send the signed SAML response -- containing user identity attributes (login name, email, roles, profile fields) -- to an attacker-controlled URL. This issue has been patched in version 5.0.9.

Weakness: CWE-601 (URL Redirection to Untrusted Site), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-41670?

2 open source packages ship an affected version, including admidio/admidio.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `admidio/admidio` | Packagist | All versions | 5.0.9 |
| `admidio/admidio` | Packagist | All versions | 5.0.9 |

## How do I fix CVE-2026-41670?

Upgrade admidio/admidio to 5.0.9 or later.

## Is CVE-2026-41670 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41670 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41670 and fix it if it is affected.

What it is: CVE-2026-41670 is a high-severity vulnerability in admidio, published on 7 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41670 exists.

Affected packages and fixed versions:
- admidio/admidio (Packagist): affected all versions; fixed in 5.0.9
- admidio/admidio (Packagist): affected all versions; fixed in 5.0.9

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-2026-41670/ (Markdown: https://insights.sbomify.com/CVE-2026-41670/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41670
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41670
- OSV: https://osv.dev/vulnerability/CVE-2026-41670

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-41670/
Summaries are generated and may contain mistakes; the official description above is the record.