# CVE-2023-43658: Improper escaping of user input in discourse-calendar

> An attacker can execute arbitrary scripts in the email preview UI if Content Security Policy is disabled, affecting Discourse forum administrators.

- **Severity:** High 8.0 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **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:** No
- **Published:** 16 Oct 2023
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-3fwj-f6ww-7hr6

## What is CVE-2023-43658?

CVE-2023-43658 is a high-severity cross-site scripting vulnerability in discourse-calendar, published on 16 Oct 2023. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

dicourse-calendar is a plugin for the Discourse messaging platform which adds the ability to create a dynamic calendar in the first post of a topic. Improper escaping of event titles could lead to Cross-site Scripting (XSS) within the 'email preview' UI when a site has CSP disabled. Having CSP disabled is a non-default configuration, so the vast majority of sites are unaffected. This problem is resolved in the latest version of the discourse-calendar plugin. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled on the forum.

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

## Which versions are affected by CVE-2023-43658?

It affects 1 product.


Products: Discourse Discourse Calendar.

## How do I fix CVE-2023-43658?

No fix has been published for CVE-2023-43658 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-43658 being exploited?

There is no known exploitation of CVE-2023-43658 in the wild and no public exploit code.

## Other vulnerabilities in discourse-calendar

- [CVE-2022-31059](https://insights.sbomify.com/CVE-2022-31059/): Discourse Calendar Event names susceptible to Cross-site Scripting (medium 6.5)
- [CVE-2024-21658](https://insights.sbomify.com/CVE-2024-21658/): Insufficient control of region value length in discourse-calendar (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-43658 and fix it if it is affected.

What it is: CVE-2023-43658 is a high-severity cross-site scripting vulnerability in discourse-calendar, published on 16 Oct 2023. 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-2023-43658 in the wild and no public exploit code.

Affected product: discourse-calendar. 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-2023-43658/ (Markdown: https://insights.sbomify.com/CVE-2023-43658/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-43658
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-43658
- OSV: https://osv.dev/vulnerability/CVE-2023-43658

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-43658/
Summaries are generated and may contain mistakes; the official description above is the record.