CVE-2023-35936 Arbitrary file write is possible in Pandoc when using PDF output or --extract-media with untrusted input
Attackers can overwrite arbitrary files via crafted input when using PDF output or media extraction, requiring untrusted input and specific flags.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2023-35936?
CVE-2023-35936 is a medium-severity path traversal vulnerability in Debian Debian Linux, published on 5 Jul 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Pandoc is a Haskell library for converting from one markup format to another, and a command-line tool that uses this library. Starting in version 1.13 and prior to version 3.1.4, Pandoc is susceptible to an arbitrary file write vulnerability, which can be triggered by providing a specially crafted image element in the input when generating files using the `--extract-media` option or outputting to PDF format. This vulnerability allows an attacker to create or overwrite arbitrary files on the system ,depending on the privileges of the process running pandoc. It only affects systems that pass untrusted user input to pandoc and allow pandoc to be used to produce a PDF or with the `--extract-media` option.
The fix is to unescape the percent-encoding prior to checking that the resource is not above the working directory, and prior to extracting the extension. Some code for checking that the path is below the working directory was flawed in a similar way and has also been fixed. Note that the `--sandbox` option, which only affects IO done by readers and writers themselves, does not block this vulnerability. The vulnerability is patched in pandoc 3.1.4. As a workaround, audit the pandoc command and disallow PDF output and the `--extract-media` option.
Weakness: CWE-20
Which versions are affected by CVE-2023-35936?
1 open source package ship an affected version, including pandoc. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
pandoc Hackage | From 1.13 | 3.1.4 |
Products include Debian Debian Linux, Pandoc Pandoc.
How do I fix CVE-2023-35936?
Upgrade pandoc to 3.1.4 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2023-35936 being exploited?
There is no known exploitation of CVE-2023-35936 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as DEBIAN-CVE-2023-35936, DLA-3507-1, GHSA-xj5q-fv23-575g, HSEC-2023-0014, JLSEC-2026-499, UBUNTU-CVE-2023-35936 and 1 more.