# CVE-2021-21383: XSS in Wiki.js

> A malicious user can inject JavaScript into Wiki.js pages via mustache expressions in code blocks, leading to stored XSS when viewed by others.

- **Severity:** High 7.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:N`)
- **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:** 18 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-6xx4-m8gx-826r

## What is CVE-2021-21383?

CVE-2021-21383 is a high-severity cross-site scripting vulnerability in Requarks wiki, published on 18 Mar 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Wiki.js an open-source wiki app built on Node.js. Wiki.js before version 2.5.191 is vulnerable to stored cross-site scripting through mustache expressions in code blocks. This vulnerability exists due to mustache expressions being parsed by Vue during content injection even though it is contained within a `<pre>` element. By creating a crafted wiki page, a malicious Wiki.js user may stage a stored cross-site scripting attack. This allows the attacker to execute malicious JavaScript when the page is viewed by other users. For an example see referenced GitHub Security Advisory. Commit 5ffa189383dd716f12b56b8cae2ba0d075996cf1 fixes this vulnerability by adding the v-pre directive to all `<pre>` tags during the render.

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

## Which versions are affected by CVE-2021-21383?

It affects 1 product.


Products: Requarks Wiki.js.

## How do I fix CVE-2021-21383?

No fix has been published for CVE-2021-21383 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21383 being exploited?

There is no known exploitation of CVE-2021-21383 in the wild and no public exploit code.

## Other vulnerabilities in Requarks wiki

- [CVE-2025-56643](https://insights.sbomify.com/CVE-2025-56643/): Security feature bypass in n/a (critical 9.1)
- [CVE-2026-44224](https://insights.sbomify.com/CVE-2026-44224/): Wiki.js: Privilege Escalation via Missing Group Validation in users.update (high 8.6)
- [CVE-2020-15236](https://insights.sbomify.com/CVE-2020-15236/): Directory Traversal in Wiki.js (high 8.6)
- [CVE-2021-43855](https://insights.sbomify.com/CVE-2021-43855/): Stored XSS via SVG in Requarks/wiki (high 8.2)
- [CVE-2021-43856](https://insights.sbomify.com/CVE-2021-43856/): Stored XSS in non-image uploads in Requarks/wiki (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21383 and fix it if it is affected.

What it is: CVE-2021-21383 is a high-severity cross-site scripting vulnerability in Requarks wiki, published on 18 Mar 2021. 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-2021-21383 in the wild and no public exploit code.

Affected product: Requarks wiki. 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-2021-21383/ (Markdown: https://insights.sbomify.com/CVE-2021-21383/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21383
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21383
- OSV: https://osv.dev/vulnerability/CVE-2021-21383

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-21383/
Summaries are generated and may contain mistakes; the official description above is the record.