# DRUPAL-CONTRIB-2019-004: The Preview Link module enables you to generate preview links so anonymous users can access unpublished revisions of content.

> Attackers can bypass access controls to view unpublished content by presenting invalid tokens in the Preview Link module.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Jan 2019

## What is DRUPAL-CONTRIB-2019-004?

DRUPAL-CONTRIB-2019-004 is an authentication bypass vulnerability in drupal/preview_link, published on 23 Jan 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Preview Link module enables you to generate preview links so anonymous users can access unpublished revisions of content.  
The last release of the module introduced an access bypass allowing users to present invalid tokens but still access unpublished content.

## Which versions are affected by DRUPAL-CONTRIB-2019-004?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `drupal/preview_link` | Packagist:https://packages.drupal.org/8 | All versions | 1.1.0 |

## How do I fix DRUPAL-CONTRIB-2019-004?

Apply the vendor's patch.

## Is DRUPAL-CONTRIB-2019-004 being exploited?

There is no known exploitation of DRUPAL-CONTRIB-2019-004 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for DRUPAL-CONTRIB-2019-004 and fix it if it is affected.

What it is: DRUPAL-CONTRIB-2019-004 is an authentication bypass vulnerability in drupal/preview_link, published on 23 Jan 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of DRUPAL-CONTRIB-2019-004 in the wild and no public exploit code.

Affected product: drupal/preview_link. 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/DRUPAL-CONTRIB-2019-004/ (Markdown: https://insights.sbomify.com/DRUPAL-CONTRIB-2019-004/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/DRUPAL-CONTRIB-2019-004

---
From sbomify Insights: https://insights.sbomify.com/DRUPAL-CONTRIB-2019-004/
Summaries are generated and may contain mistakes; the official description above is the record.