# CVE-2026-91120: Discourse: Stored HTML injection in video notification emails

> Attackers can inject HTML into video notification emails via malicious titles, potentially executing scripts in recipients' email clients.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** BIT-discourse-2026-91120, GHSA-h7cg-2vww-m45c

## What is CVE-2026-91120?

CVE-2026-91120 is a medium-severity cross-site scripting vulnerability in discourse, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, provider-controlled video titles in lazy video embeds could be reparsed as HTML when Discourse generated notification emails or chat summaries. A user with standard posting privileges could create a post for an enabled YouTube, Vimeo, or TikTok provider whose title contained markup, and the email and chat-summary rendering path would place that markup into the output instead of treating it solely as text. Recipients using HTML-capable email clients could see injected content, potentially including event handlers, but the issue did not directly expose a Discourse browser session or affect the forum page itself. Lazy video embeds must be enabled, which is the default configuration. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-91120?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `discourse` | Bitnami | All versions | 2026.8.0 |

## How do I fix CVE-2026-91120?

Upgrade discourse to 2026.8.0 or later.

## Is CVE-2026-91120 being exploited?

There is no known exploitation of CVE-2026-91120 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91120 and fix it if it is affected.

What it is: CVE-2026-91120 is a medium-severity cross-site scripting vulnerability in discourse, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-91120 in the wild and no public exploit code.

Affected packages and fixed versions:
- discourse (Bitnami): affected all versions; fixed in 2026.8.0

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-2026-91120/ (Markdown: https://insights.sbomify.com/CVE-2026-91120/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91120
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91120
- OSV: https://osv.dev/vulnerability/CVE-2026-91120

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91120/
Summaries are generated and may contain mistakes; the official description above is the record.