CVE-2021-38186
XSS in `comrak`
Description
[comrak](https://github.com/kivikakk/comrak) operates by default in a "safe" mode of operation where unsafe content, such as arbitrary raw HTML or URLs with non-standard schemes, are not permitted in the output. This is per the reference GFM implementation, [cmark-gfm](https://github.com/github/cmark). Ampersands were not being correctly escaped in link targets, making it possible to fashion unsafe URLs using schemes like `data:` or `javascript:` by entering them as HTML entities, e.g. `data:`. The intended behaviour, demonstrated upstream, is that these should be escaped and therefore harmless, but this behaviour was broken in comrak.
How to fix CVE-2021-38186
To remediate CVE-2021-38186, upgrade the affected package to a fixed version below.
- —upgrade to 0.10.1 or later
- —upgrade to 0.10.1 or later
Is CVE-2021-38186 being exploited?
Low — EPSS is 0.7%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0, < 0.10.1
- >= 0.0.0-0, < 0.10.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |