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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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.
Which versions are affected by CVE-2021-29475?
It affects 1 product.
Products include 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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
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
Sources
Also known as GHSA-pxxg-px9v-6qf3.