# CVE-2021-29475: PDF export allows arbitrary file reads

> Attackers with note modification rights can read arbitrary files via PDF export, exposing sensitive configuration data.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-pxxg-px9v-6qf3

## What is CVE-2021-29475?

CVE-2021-29475 is a critical server-side request forgery vulnerability in hedgedoc, published on 26 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor. An attacker is able to receive arbitrary files from the file system when exporting a note to PDF. Since the code injection has to take place as note content, there fore this exploit requires the attackers ability to modify a note. This will affect all instances, which have pdf export enabled. This issue has been fixed by https://github.com/hedgedoc/hedgedoc/commit/c1789474020a6d668d616464cb2da5e90e123f65 and is available in version 1.5.0. Starting the CodiMD/HedgeDoc instance with `CMD_ALLOW_PDF_EXPORT=false` or set `"allowPDFExport": false` in config.json can mitigate this issue for those who cannot upgrade. This exploit works because while PhantomJS doesn't actually render the `file:///` references to the PDF file itself, it still uses them internally, and exfiltration is possible, and easy through JavaScript rendering. The impact is pretty bad, as the attacker is able to read the CodiMD/HedgeDoc `config.json` file as well any other files on the filesystem. Even though the suggested Docker deploy option doesn't have many interesting files itself, the `config.json` still often contains sensitive information, database credentials, and maybe OAuth secrets among other things.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2021-29475?

It affects 1 product.


Products: Hedgedoc Hedgedoc.

## How do I fix CVE-2021-29475?

No fix has been published for CVE-2021-29475 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-29475 being exploited?

There is no known exploitation of CVE-2021-29475 in the wild and no public exploit code.

## Other vulnerabilities in hedgedoc

- [CVE-2020-26287](https://insights.sbomify.com/CVE-2020-26287/): Stored XSS in mermaid diagrams (high 8.7)
- [CVE-2021-39175](https://insights.sbomify.com/CVE-2021-39175/): XSS vector in slide mode speaker-view (high 8.1)
- [CVE-2021-29503](https://insights.sbomify.com/CVE-2021-29503/): Improper Neutralization of Script-Related HTML Tags in Notes (high 8.1)
- [CVE-2020-26286](https://insights.sbomify.com/CVE-2020-26286/): Arbitary file upload (high 7.5)
- [CVE-2021-21259](https://insights.sbomify.com/CVE-2021-21259/): Stored XSS in slide mode (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-29475 and fix it if it is affected.

What it is: CVE-2021-29475 is a critical server-side request forgery vulnerability in hedgedoc, published on 26 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-29475 in the wild and no public exploit code.

Affected product: hedgedoc. 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-2021-29475/ (Markdown: https://insights.sbomify.com/CVE-2021-29475/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-29475
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-29475
- OSV: https://osv.dev/vulnerability/CVE-2021-29475

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-29475/
Summaries are generated and may contain mistakes; the official description above is the record.