cve/2023/CVE-2023-42821.md

### [CVE-2023-42821](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-42821)
![](https://img.shields.io/static/v1?label=Product&message=markdown&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=%3D%20%3C%200.0.0-20230922105210-14b16010c2ee%20&color=brighgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=CWE-125%3A%20Out-of-bounds%20Read&color=brighgreen)

### Description

The package `github.com/gomarkdown/markdown` is a Go library for parsing Markdown text and rendering as HTML. Prior to pseudoversion `0.0.0-20230922105210-14b16010c2ee`, which corresponds with commit `14b16010c2ee7ff33a940a541d993bd043a88940`, parsing malformed markdown input with parser that uses parser.Mmark extension could result in out-of-bounds read vulnerability. To exploit the vulnerability, parser needs to have `parser.Mmark` extension set. The panic occurs inside the `citation.go` file on the line 69 when the parser tries to access the element past its length. This can result in a denial of service. Commit `14b16010c2ee7ff33a940a541d993bd043a88940`/pseudoversion `0.0.0-20230922105210-14b16010c2ee` contains a patch for this issue.

### POC

#### Reference
- https://github.com/gomarkdown/markdown/security/advisories/GHSA-m9xq-6h2j-65r2

#### Github
No PoCs found on GitHub currently.