# CVE-2026-12804: lemonldap-ng SAML Common Domain Cookie Endpoint CDC.pm redirect

> Remote attackers can exploit an open redirect in the SAML Common Domain Cookie Endpoint, though impact is low as the feature is rarely used.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P`)
- **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:** 21 Jun 2026
- **Updated:** 22 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-12804, GHSA-g4v8-q2mr-m933, UBUNTU-CVE-2026-12804

## What is CVE-2026-12804?

CVE-2026-12804 is a medium-severity vulnerability in lemonldap-ng, published on 21 Jun 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

A vulnerability was detected in lemonldap-ng up to 2.23.0. Impacted is an unknown function in the library lemonldap-ng-portal/lib/Lemonldap/NG/Portal/CDC.pm of the component SAML Common Domain Cookie Endpoint. Performing a manipulation of the argument url results in open redirect. The attack is possible to be carried out remotely. The exploit is now public and may be used. Applying a patch is the recommended action to fix this issue. The vendor confirms, that "it has been fixed some days ago and will be available in 2.23.1. CDC is quite never used, so the impact is very low."

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-12804?


## How do I fix CVE-2026-12804?

Apply the vendor's patch.

## Is CVE-2026-12804 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-12804 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12804 and fix it if it is affected.

What it is: CVE-2026-12804 is a medium-severity vulnerability in lemonldap-ng, published on 21 Jun 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-2026-12804 exists.

Affected product: lemonldap-ng. 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-2026-12804/ (Markdown: https://insights.sbomify.com/CVE-2026-12804/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12804
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12804
- OSV: https://osv.dev/vulnerability/CVE-2026-12804

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-12804/
Summaries are generated and may contain mistakes; the official description above is the record.