# CVE-2025-66488: Discourse allows script execution in uploaded HTML/XML files on S3

> Attackers can execute scripts via uploaded HTML/XML files on S3, impacting users on the CDN domain.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 28 Jan 2026
- **Updated:** 28 Jan 2026
- **Also known as:** BIT-discourse-2025-66488, GHSA-68jp-3934-62rx

## What is CVE-2025-66488?

CVE-2025-66488 is a medium-severity cross-site scripting vulnerability in Discourse Discourse, published on 28 Jan 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider deleting them.

Weakness: CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2025-66488?

1 open source package ship an affected version, including discourse. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | All versions | 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0 |

Products: Discourse Discourse.

## How do I fix CVE-2025-66488?

Upgrade discourse to a fixed version for your release line: 3.5.4, 2025.11.2, 2025.12.1 or 2026.1.0.

## Is CVE-2025-66488 being exploited?

There is no known exploitation of CVE-2025-66488 in the wild and no public exploit code.

## Other vulnerabilities in Discourse Discourse

- [CVE-2021-41163](https://insights.sbomify.com/CVE-2021-41163/): RCE via malicious SNS subscription payload (critical 10.0)
- [CVE-2022-36066](https://insights.sbomify.com/CVE-2022-36066/): Discourse vulnerable to RCE via admins uploading maliciously zipped file (critical 9.1)
- [CVE-2022-39356](https://insights.sbomify.com/CVE-2022-39356/): Discourse user account takeover via email and invite link (high 8.9)
- [CVE-2023-22468](https://insights.sbomify.com/CVE-2023-22468/): Discourse vulnerable to Cross-site Scripting in local oneboxes (high 8.8)
- [CVE-2026-27934](https://insights.sbomify.com/CVE-2026-27934/): Discourse leaks private topic title and post excerpt via user action API endpoint (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-66488 and fix it if it is affected.

What it is: CVE-2025-66488 is a medium-severity cross-site scripting vulnerability in Discourse Discourse, published on 28 Jan 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-66488 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected all versions; fixed in 3.5.4, 2025.11.2, 2025.12.1, 2026.1.0

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-2025-66488/ (Markdown: https://insights.sbomify.com/CVE-2025-66488/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-66488
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-66488
- OSV: https://osv.dev/vulnerability/CVE-2025-66488

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-66488/
Summaries are generated and may contain mistakes; the official description above is the record.